Following the general custom of men of standing in Florence, Filippo learned to read and write at an early age and to use the abacus.  He also learned some Latin; perhaps because his father, who was a notary, thought of having him follow the same profession, since very few men of that period took up Latin--or were made to take it up--unless they expected to become a doctor, notary, or priest.  He was very obedient, manageable, and fearful of disgrace.  That fear was more effective than threats or any other device.  He longed for distinction in whatever he undertook.  From childhood he had a natural interest in drawing and painting and his work was very charming.  For that reason he elected to become a goldsmith when his father, as was the custom, apprenticed him to a trade.  Noting his aptitude, his father, who was a wise man, gave his consent.

Because of his foundation in drawing he quickly became very proficient in that profession in which he soon displayed himself most wonderfully....  It was in general the same in everything he dedicated himself to....  In that art and what pertained to it he succeeded more marvelously than seemed possible at his age....

Since ... he revealed a marvelous genius, his advice about buildings was in great demand....

During the same period he propounded and realized what painters today call perspective, since it forms part of that science which, in effect, consists of setting down properly and rationally the reductions and enlargements of near and distant objects as perceived by the eye of man:  buildings, plains, mountains, places of every sort and location, with figures and objects in correct proportion to the distance in which they are shown.  He originated the rule that is essential to whatever has been accomplished since his time in that area.  We do not know whether centuries ago the ancient painters--who in that period of fine sculptors are believed to have been good masters--knew about perspective or employed it rationally.  If indeed they employed it by rule ... as he did later, whoever could have imparted it to him had been dead for centuries and no written records about it have been discovered, or if they have been, have not been comprehended.  Through industry and intelligence he either rediscovered or invented it....

Although he was preeminent over many others in many things and consequently refined his own and the following century, he was never known to boast or praise himself or vaunt or laud himself by a single word.  Instead he proved himself by his deeds with the opportunities that came along.  Unless greatly provoked by insulting or disrespectful acts, he never became angry and was amiable to his friends.  It gave him pleasure to commend those who merited it.  He willingly instructed those he thought wished to be instructed and who were capable of instruction.  He was very skillful. and discerning in that as he was in other things....

[H]e went to Rome where at that time one could see beautiful works in public places.  Some of those works are still there, although not many; some have been removed, carried off, and shipped out by various popes and cardinals from Rome and other nations.  In studying the sculpture as one with a good eye, intelligent and alert in all things, would do, he observed the method and the symmetry of the ancients' way of building.  He seemed to recognize very clearly a certain arrangement of members and structure just as if God had enlightened him about great matters.  Since this appeared very different from the method in use at that time, it impressed him greatly....

He decided to rediscover the fine and highly skilled method of building and the harmonious proportions of the ancients and how they might, without defects, be employed with convenience and economy.  Noting the great and complex elements making up these matters--which had nevertheless been resolved--did not make him change his mind about understanding the methods and means they used.  And by virtue of having in the past been interested and having made clocks and alarm bells with various and sundry types of springs geared by many diverse contrivances, he was familiar with all or a great number of these contrivances, which helped him a great deal in conceiving different machines for carrying, lifting, and pulling, according to what the exigencies were.  He committed some of them to memory....  He saw ruins ... which had been vaulted in various ways.  He considered the methods of centering the vaults and other systems of support, how they could be dispensed with and what method had to be used, and when--because of the size of the vault or for other reasons--armatures could not be used....  By his genius, through tests and experiments, with time and with great effort and careful thought, he became a complete master of these matters in secret, while pretending to be doing something else....

The sculptor Donatello was with him almost all the time during this stay in Rome....

During the period that Filippo ... stayed in Rome, he made many trips to Florence....  Every time he went there ... his opinion on day-to-day problems concerning private and public buildings required at the time were requested, because of the reputation of his fine intellect and because of those who had known him earlier....  Through giving his opinion and demonstrating his ingenious devices, his fame constantly increased.  Therefore, in 1417 when he happened to be there again, the operai, on hearing of his return, sent for him for--having arrived at the tambour oculi--the time was approaching to vault the octagon.  Together with the master builders and the other officials concerned, they took great pleasure in discussing it with him, particularly because the problems of vaulting such a great and lofty space were already on the minds of the master builders.  considering the height and width, and the great weight of the struts and supports of the centering armature and other supports--necessitating their rising from ground level--the [amount of] wood and the cost not only seemed fantastic, but because of the problems, almost impossible--or better, completely impossible.  Therefore the master builders felt that the operai should discuss it with Filippo, and so they did.  Although the builders noted some of the difficulties, Filippo pointed out many more to them.  someone remarked:  Well then, is there no way to vault it?  Filippo's responses were of such a nature--he was also skillful in reasoning--that when the impossibility was obvious he clearly pointed it out [saying, however] that when they were ready there would certainly be someone on earth to vault it, since Almighty God, to whom nothing was impossible, would not forsake us, as it is a sacred edifice.  Noting that the operai were somewhat affected by these words Filippo said that urgent business required his return to Rome.  However they would not let him go.  They kept him so long, seeing him at all hours almost every day, that in order not to appear ungrateful they made him accept ten gold florins in recompense when he finally departed....

Returning to Rome and thinking over what had been done in regard to architecture in the past and what had been attempted, as has been noted, by other gifted men in the opera and elsewhere, he did not feel that he had wasted his time.  Although he had worked very hard in the past, now with the aforementioned church in Florence always in his thoughts and with some expectation of having to take care of it, he worked harder than ever.  With the greatest industry he investigated the methods that the ancient masters employed in the problems he encountered and he noted various solutions....

When in 1419 the operai heard that Filippo was again in Florence on business, they wanted to retain him since the tambour was almost finished, and they had to consider vaulting the cupola.  They asked him to think about it.  Because of the great difficulty and because of the honor, and in order not to waste money and because the work merited it, Filippo responded by urging them to convoke soon ... an assembly of masters, architects, masons, and master engineers from all Christendom and to confer with them in the presence of a large number of the most worthy men of the city ... and perhaps God might bless it.  These experts should be recruited in seasonable time and the date and compensation for those attending should be fixed by the merchants and the Signoria.  And with this advice he departed....

Having finished building the eight sides of the tambour, the operai and officials in charge summoned a council of selected citizens [to consider] the problems of vaulting it in advance so the work would not be delayed....

After a few months they had the information and a day was designated far enough in the future to allow time for arrival from all points.  Prizes of such a nature were offered that ... many masters of building and engineering and similar professions were there.  Filippo came from Rome.  He conferred and discussed the problem a great deal:  above all how it had to be done.  Intermingled with such matters he had to discuss many details:  light's stairways; centering; chains of various kinds such as wood, iron, and stone; drainage; as well as decorations, and the provision--after the erection of the vault--for the accommodation of the choir, the altars, and the decorations for the Feast Days; and similarly for the plaster surface which in time would require mosaics or paintings; and for the construction of hanging and ground-based scaffolding.

After all these very important considerations and preparations ... they came to the problem of how to vault it--that great, heavy, double vault, which is of such great weight throughout.  That the vault had to be supported with centering was taken for granted by all the masters except Filippo.  And since each master expressed his own opinion of what method to use, two conclusions were drawn from Filippo's speech.  The first being that such a great undertaking could not be accomplished with centering:  the second being that they were obliged, if they wished to vault it, to do so without centering.

Not having proved himself in any large undertaking comparable to this building ... and not having sufficient influence at that time to satisfy everyone, he was ridiculed by the operai and other ordinary citizens and no less by our own masters than by the foreign masters....  From Filippo's words the operai unanimously drew the conclusion that a large building of such a character could not be completed and that it had been naïve of earlier masters and those who relied on them to believe [that it could be finished].

When Filippo protested against this erroneous conclusions which he saw they had accepted, and when he told them it could be done, they united in one in asking:  How will it be supported?  He repeated constantly that it could be vaulted without centering.  After many days of standing firm--he in his opinion and they in theirs--he was twice angrily carried out by the servants of the operai and of the Wool Merchants Guild, the consuls, and many others present, as if he were reasoning foolishly and his words were laughable.  As a consequence he was later often wont to say that during the period in which that occurred ... he was ashamed to go about Florence  He had the feeling that behind his back they were saying:  Look at that mad man who utters such nonsense....

Seeing his persistence, some people began to heed him, especially because of the difficulty and almost impossibility demonstrated generally ... by all the others:  one, for example, said that he wanted to vault it by filling up the space inside with earth which would hold it up like formwork; another said that a tower should be constructed in the middle and the centering suspended from it.  Others proposed various diverse methods until everyone was almost desperate....

They began to accept the reasons he had outlined and to ask whether he might not be trusted in the great undertaking if he could provide some confirmation in a small undertaking [namely, by showing them what he could do in constructing a chapel in San Jacopo di Borgo Oltrarno]....

Because of this test, [people] partly began to trust his words, although not completely, since the chapel was a small undertaking and the other a great one which, as far as is known, was without precedent.

Finally after other experiments ... he was asked about the procedure [for vaulting] such a great thing without centering, with a double vault and a lantern....  Filippo reasoned orally with great conscientiousness and precision, and finally he was requested to put down in writing the method of keeping it steady and firm so that it would not slip.  He did not make any difficulty about this [request], and the written detailed information was handed over to them....  A copy of it in proper form follows.

As was stated, the city was divided....  Some had great confidence in Filippo and some had confidence in Lorenzo [Ghiberti (1378-1455)] because of his work on the San Giovanni doors, which had come out well....  They began to say that the best and surest decision would be to appoint a colleague....  Lorenzo's friends had so much influence (so heated was the rivalry) that he was appointed as Filippo's partner for the fourteen braccia test....

Secretly, and also to some degree publicly, Filippo and those supporting him expressed great dissatisfaction that the decision had been made in this way.  However, that is how the matter went.

Commencing preparations for the work, Filippo decided to make a small wooden model for the cupola....

When the time arrived to build the eight-sided wall going from the oculi up to the springing of the cupola vault Filippo persisted in his unwavering belief that some way or other the work would be in his hands, since the project was completely his and could not be managed in any other way....  With marvelous skill he bound the outer shell to the inner shell as there had to be two vaults, and there we find many macigno stones, set transversely with various interlocking courses and connections....

Later, when the construction of the double vaults of the dome was begun a few braccia were completed without difficulty or fear on the part of the workmen, since [the vaults] were almost perpendicular.  However, they had not got very far when two important things occurred.  Both the danger and the apprehension of the masters and the other men working there constantly increased because of the absence of trusswork or parapets under them.  The height aroused more than a little fear.  These two important things were:  first, the construction of working platforms to take the place of those that had been erected to begin with on the first level; and secondly, the construction of chains that, as Filippo's reported stated, appeared to be necessary to encircle the covered cupola....

Filippo did not leave his bed one morning.  He remained there pretending to be ill, of a pain in his side in particular.  Whereas he was usually the first one at work he complained and had pads heated and other like preparations and remedies for such ailments made.

Since it was necessary at almost every point to ask about the work, they turned to Lorenzo as Filippo was not there.  Lorenzo knew that the organization of the work was Filippo's and had to be followed; however, Filippo kept it to himself as far as he was able and Lorenzo did not like to ask about it for fear of appearing ignorant.  He knew Filippo did not want him there and would not have told him.  He did not want to make a mistake through anything he said, because Filippo would be annoyed that his program had been interrupted, and later some conspicuous thing might have to be dismantled and he would be disgraced and Filippo would gain in honor and reputation--which he already had too much of, in his opinion.  Not knowing what to do, it was urged that Filippo be entreated to come....  As every hour Filippo pretended to be worse the matter went so far that a large part of the work stopped and much alarm was aroused in the opera.  When something about it was said to Filippo's friends they said:  Well, is Lorenzo not there?  If Filippo is ill, is that his fault?  No one is more unhappy about that than he is.  And those on the opposite side charged that Filippo was pretending to be sick because he was sorry he had undertaken such an enterprise:  that he had undertaken it in order to appear more amazing than he was and that now he did not have the courage to go through with it.  It was easy for them to gain credence for this opinion since it still seemed impossible to many that he would succeed.  After some days, he came to the opera with a great show of difficulty.  He declared that the illness might return at any time God willed and that it might equally befall Lorenzo.  He proposed that for the good of the building, and inasmuch as the salary was divided, the day-to-day problems should also be divided so the work could go forward without interruption and damage.  The principal and immediate requirements were the scaffolding and the program of building, and a chain to encircle the [inner] cupola....  Lorenzo could take charge and oversee whichever one of these he wished and he would take charge of the other.  Therefore Lorenzo was forced to agree to this division.  He chose to make the chain, hoping to do it correctly on the basis of the one in San Giovanni, since he had no knowledge of scaffolding:  he did not know what had to be done or the extraordinary way in which it had to be constructed.  When he said he wanted to take charge of the chain Filippo exclaimed:  Very well!  And I will take charge of the scaffolding and the masonry work.

Lorenzo applied himself to his task and made it just the way the one in San Giovanni appeared to him to be made....  Filippo for his part made the scaffolding for the construction and went forward.  Those scaffolds were of new and necessary forms.  Thus with the new methods of building and with protection from peril there was no apprehension, and the work went forward.

When the time arrived for installing the chain it was put in place.  When it had been installed and everything made ready, Filippo carefully considered it.  It did not seem to him that it met the requirements adequately and thus it would have to be made differently.  He began, albeit courteously, to spread word among his supporters that the chain was worthless and had to be completely remade.  He convinced them in such a way that after he saw that they fully understood he demonstrated that Lorenzo and the provision made to him were harmful:  firstly, because the entire cost of the chain, which was not small, was thrown away and secondly, because the expenditure of thirty-six florins a year on Lorenzo was an expenditure that could be eliminated.  The operai therefore commissioned Filippo to show them how it had to be constructed in order to meet the requirements.  He demonstrated it so clearly that the chain was put in his charge and he made it to complete perfection....

He performed such experiments and gave such proof of himself that by the time that he had hardly reached half of the fourteen braccia, it was unanimously agreed--with the consent of the operai and the consuls and the entire membership of the Wool Guild and of all the citizens--to commission him to complete it, as well as to construct the lantern and everything pertaining to the building of the church....

Being aware that they had to vault the cupola, the principal bricklaying masters joined together, saying that each one of the eight façades of the cupola would have to be allocated to a single master of bricklaying.  Actually, that was the intention of Filippo and the operai....

Those bricklaying masters, having selfishly unionized themselves, decided to serve their own interests [i.e., went on strike for higher pay], but it had not proceeded very far when they were challenged, since Filippo had become aware of the situation.  He said to them:  For your own advantage and to the harm of the enterprise you have joined together, thinking that without you it could not be built.  However, it cannot succeed except by the correct method.  Consequently as I cannot have you, I will have it built by eight Lombards.  And he started to work with the Lombards and trained and adapted them to his methods.  As a result those fellows recognized their error and were satisfied with reasonable working arrangements and in that spirit were rehired.  Thus the work went forward by means of Filippo's amazing diligence and prudence.

The astonishing aspect of his arrangement was that nothing new for him appeared to be in it, but that it seemed as if he had done other similar things in his earlier career.  Between the shells of the cupola, both toward the inside of the church and on the tiled outside surface as well as [hidden] in its [shells], are diverse provisions and devices in various places.  The hidden [devices] are much more numerous than the exposed:  for protection against wind, earthquake, and its own weight--which could be harmful [with respect] to what is below in a [particular] place, and more with respect to the things piled up above [in their relation] to the things below.  There are many stones and concealed [devices] in the angles which are not evident to anyone, while others can be seen.  Those that can partially be seen are long macigno beams.  When he discussed these with the stonemasons they could not understand him at all.  [He made some models for them] in soft clay and then in wax and wood.  Actually those large turnips, called goblets, which come on the market in Winter were useful for making the small models and for explaining things to them.  For that purpose he also went to the iron-mongers for various and diverse objects in iron which even the craftsmen understood with difficulty.  He then was with the joiners with new methods and new conceptions and provisions for various kinds of objects that it was believed no one else had ever conceived of:  e.g., lights for use in areas for climbing up and down and avoiding bumps, falls in the dark, and all shocks and dangers to those who had to go to those places.  They were useful not only for avoiding danger, but  also for freeing those who used them from fear and apprehension.  And in order that the apprentices and masters, who paid their own expenses, would not lose time he arranged for cooks to be there and for wine and bread to be sold to those who did not come prepared.  Thus every provision was made so that nothing would be lacking and no time would be spent in idleness.

By these means and many others he proceeded in such a way that the completion of the cupolas arrived with great beauty, with strength, with provisions for any eventuality, with savings for the opera, without defect, with the great satisfaction of everyone--whether knowledgeable or ignorant--who saw it, and with the greatest fame and glory for himself.  Everyone believed that only one person in the world could have accomplished it and that was the one who had done it....

During his life not a small stone or brick was placed which he did not wish to examine to see whether it was correct and if it was well-fired and cleaned:  something which no care was expended upon afterward, since today attention is paid only to what appears to be economical, and stones from the river and rough bricks and all sorts of crudity are employed.  The care he gave to the mortar was wonderful.  He personally went to the brickyards regarding the stones and the baking, the sand and lime mixture, and whatever was required.  He seemed to be the master of everything....