The usual account starts with genius and works outwards. This one starts with cloth, because that is where the money started.
Florence made its first fortune not by weaving but by finishing: buying rough cloth from northern Europe, then dyeing and dressing it to a quality nobody else could match, and selling it across the Mediterranean. That required capital, organisation, and a large workforce of wage labourers in a single industry, which is unusual for the thirteenth century and had political consequences of its own.
The second fortune was banking, and it grew out of the first. Merchants who moved cloth needed to move money, and the instruments of chapter sixteen, the bill of exchange and double entry accounts, were refined here. By the early fourteenth century Florentine houses had branches across Europe and were lending to kings.
That was dangerous. In the 1340s the two largest houses collapsed, in part because the king of England defaulted on enormous war loans, and the failure took much of the city's wealth with it. Sovereign lending has been a way to lose a bank for a very long time.
The third fortune, the one attached to the famous name, was built after that crash and was more careful about it.
The Medici were not princes and for most of their ascendancy they held no permanent office. Florence was a republic with an elaborate constitution designed specifically to stop anyone dominating it: short terms, selection of officials by drawing names from bags, and exclusion of the old noble families from government.
Cosimo de' Medici, who ran the bank from the 1430s, worked inside that machinery rather than against it. His instruments were credit and marriage. He lent to men who mattered, arranged their daughters' dowries, paid their tax bills, and in return they voted his way and made sure the names in the bags were acceptable. Contemporaries understood exactly what was happening and had no legal remedy for it, because nothing he did was illegal.
The bank itself was cleverly built. Each branch was a separate partnership with local partners holding a share, which meant that a failure in Bruges did not automatically bring down Rome, and which gave the men running each branch a reason to be careful. Its most profitable business was handling the papal accounts, which is worth noticing given how often the church is presented as an obstacle to commerce.
It ended as such arrangements do. His grandson Lorenzo was a better politician than banker, branches failed under poor managers, and money was moved from the bank to cover political obligations. Two years after Lorenzo's death the family was expelled from the city.
Four reasons, and they are not mutually exclusive.
Salvation, which was more pressing than modern readers assume. Lending at interest was a sin, and men who had made fortunes doing it were told so from the pulpit. Funding a chapel, an altarpiece or a hospital was a recognised way of setting the books right. The most famous chapel in Padua was built by the son of a notorious moneylender on the site of a Roman arena, and the family's own theology of the transaction is not hidden.
Status, in a city where the old aristocracy had been excluded from office and the new money had no titles. If you cannot be a marquis you can be the man who paid for the facade.
Politics. For a family governing without holding office, public generosity was the visible argument for its position. The buildings were the campaign.
And civic competition. Much of the greatest work was commissioned not by individuals but by guilds and by the city itself, in explicit rivalry with other cities and with each other. The competition for the bronze doors of the baptistery in 1401 was a public contest with a jury, and the sculptor who lost went off to think about architecture and later built the dome.
The romantic idea of the artist arrives later. In this period a painter was a member of a guild, trained by apprenticeship, running a workshop with assistants, and working to a written contract.
The contracts survive in numbers and they are wonderfully unromantic. They specify the subject and who appears in it, the date of delivery, the penalty for lateness, how much of the work must be by the master's own hand rather than assistants, and, at length, the materials. Ultramarine blue, made from lapis lazuli imported from Afghanistan, cost more than gold by weight and is specified by the ounce and by grade. Gold leaf is counted.
Read a few and the priorities become plain. The patron was buying quantity of expensive material and a guarantee of the master's personal attention, in that order. What we would call originality is barely mentioned.
What changed over the century is that the standing of the best practitioners rose until some of them could dictate terms, refuse commissions, and be courted by rulers. The shift from craftsman to artist is visible in the contracts themselves, and it is one of the genuine novelties of the period.
The technical changes were real and are precisely datable. A demonstration of linear perspective using a painted panel and a mirror, around 1413, gave painters a geometric method for representing depth, and a treatise of 1435 wrote the rules down so anyone could learn them. Oil painting, developed further in the Netherlands, arrived and allowed glazing, subtle light and correction. Dissection, permitted under conditions, improved anatomy.
One building is worth a section, because it shows both the achievement and what it sat on.
The cathedral of Florence had been under construction since 1296 with a hole at the top. The intended dome was to span more than forty metres, higher and wider than anything built since antiquity, and nobody knew how to do it. The standard method, a timber framework supporting the masonry until the mortar set, would have required more large timber than was available and a structure nobody could build.
The solution, worked out by a goldsmith turned architect who had lost the baptistery competition, was to build it without that framework: two shells, one inside the other, a herringbone brick pattern that locked each course so it would not slide inward while wet, and rings of stone and iron chain around the base acting in tension like barrel hoops. It took sixteen years and it is still standing.
Now the part usually left out. The men who built it were paid daily wages by the wool guild, which financed and supervised the cathedral works, and the same guild governed an industry in which thousands of textile workers had no representation of any kind. In 1378 those workers had risen, seized the government for six weeks, and demanded the right to form a guild of their own. The revolt was crushed and the concessions revoked, and the city's constitution was tightened afterwards to make sure it could not happen again.
So the dome and the exclusion were built by the same institution in the same generation. That is not a paradox to be resolved; it is the ordinary condition of the period, and a chapter that reports the first without the second is describing a facade.
Alongside the painting, a movement in scholarship that called itself the study of the humanities, and which is where the word humanism comes from.
Its programme was to recover classical Latin and Greek literature, in accurate texts, and to read it as literature and moral instruction rather than as raw material for logical analysis. Its practitioners scoured monastic libraries for forgotten manuscripts and found things: a complete text of a Roman handbook on oratory in 1416, and in 1417 a long philosophical poem by Lucretius, arguing that the universe is made of atoms moving in a void and that the gods do not intervene, which had been effectively lost for a thousand years.
They also learned Greek properly, which western Europe had largely not done, helped by teachers arriving from a shrinking Byzantine Empire. And they developed the beginnings of textual criticism: in 1440 one of them demonstrated on linguistic grounds that a document the papacy had relied on for centuries, purporting to record the emperor Constantine's donation of the western empire to the church, was a forgery, because its Latin was not fourth century Latin.
That is a genuinely new intellectual weapon. It says that a document can be interrogated by the historical characteristics of its own language, and that authority cannot protect a text from that examination. Chapter twenty five is downstream of it.
It is worth saying what humanism was not. It was not anti religious. Most humanists were devout, many were clergy, and one became pope. The programme was to read the classics and the scriptures in better texts and better languages, and it was carried out largely by people who thought this would strengthen Christianity, not replace it.
The end of the republic makes the point again. In 1494 a Dominican preacher named Savonarola took effective control of the city on a programme of moral reform, and for four years Florence burned its own luxuries in the square, including books and paintings that artists brought voluntarily. Then the mood turned, he was excommunicated, tortured, hanged and burned on the same spot. The city that had produced the century's art destroyed some of it, and then destroyed the man who had asked for it, within four years.
Firm: the documents. Florence has an extraordinary archive. Tax returns from 1427 survive for the whole city, household by household, with declared assets. Bank ledgers, guild records, commission contracts and private letters exist in quantity. We know what individual paintings cost and who paid.
Soft: the intentions behind patronage. Contracts record terms, not motives, and the salvation argument is inferred from what people said in other contexts.
Contested: the word Renaissance. It was popularised in the nineteenth century, and it carries a claim, that this was a rebirth after a dead interval. Chapters nine, sixteen and seventeen are the argument against that claim: the twelfth and thirteenth centuries had their own recovery of classical material, their own economic expansion and their own intellectual revolution. The humanists invented the idea of a dark middle age because it flattered them, and historians repeated it for four hundred years.
What survives of the term, used carefully, is real enough: a concentrated change in visual art, in the study of ancient texts, and in the status of the people doing both, in a particular set of Italian cities, funded by commercial wealth.
Contested: whether the money explains the art. Plenty of cities were rich. Bruges and Antwerp were richer than Florence for much of the period and produced a different and equally remarkable art. Wealth was necessary and it was not sufficient, and any account that reduces the second half of this chapter to the first is doing the same trick in reverse.
One absence to name: women. They appear in this chapter as dowries and as subjects of portraits. They were excluded from the guilds, the workshops, the universities and the public commissions, with a handful of exceptions later in the period. The talent pool was halved by rule.