Born in 1497, Matthäus was a member of the burgher (or middle) class. From the age of 23, he kept the books for a man named Fugger the Rich, the head of a famous merchant family whose wealth put them on a par with royalty (they are remembered as “the Medici of the North.”) Almost from his first day on the job, he began work on the Klaidungsbüchlein—an illuminated manuscript consisting of loose pages measuring approximately four by six inches, each bearing a full-length miniature portrait.

The images aren’t selfies in the technical sense; Matthäus was an accountant, not an artist, and he enlisted a succession of four local painters to produce the images (the first died of the plague in 1536). But they are, effectively, self-portraits, and selfies in the spiritual sense: Matthäus chose the costume, postures, details, and backgrounds he wanted included, and even commented on the artists’ work (“The face is well captured.”) In this fashion, he assembled 137 images of himself over 40 years—a selfie record unmatched until the advent of photography.

When Martin Luther complained that Germans spent too much money on imported luxury goods, he may well have been thinking of Matthäus, who often noted the cost of his garments and seems to have taken pride in recording tailoring bills in excess of the materials, a new and important benchmark of luxury at the time. Matthäus never met a Spanish cape or Siberian squirrel-fur lining he didn’t like. The book depicts suits of armor, embroidered shirts, reversible garments, and hose trimmed with fringe, ornamental metal aglets, or little bells. Such was Matthäus’s addiction to colorful headgear that male friends sometimes gave him caps as gifts, which were then depicted and described in breathless detail in the book. (One, he notes sadly, was later “pushed into some cow dung. It was useless.”)

Though Matthäus’s wardrobe seems to have been typical for his time and place, that milieu occupies a rather unique niche in fashion history. With its thriving textile and metalwork industries and its proximity to Italy, Augsburg was, for a brief period between the late 15th century and the Reformation, home to some of the most elaborate male fashions ever worn. The book is bursting with color, asymmetry, stripes, and decorative paning, pinking, and slashing; one especially fabulous white doublet is slashed 4,800 times. The period saw the development of specialist sportswear for fencing, archery, and sledding—activities that required leisure time and permitted social networking. The Klaidungsbüchlein depicts these over-the-top fashions much more precisely and clearly than even Augsburg’s own Hans Holbein, who was one of the century’s greatest portraitists.

But fashion wasn’t just an idle pastime or foppish indulgence. It conveyed a multitude of messages, from the financial to the political. Since part of the Fugger merchant empire involved the international textile trade, Matthäus may have boosted his career by advertising the company’s wares. He often strategically selected his outfits to appeal to visiting politicians, wearing the French colors of yellow and blue to welcome King Francis I to Milan, and even commissioning six new outfits to impress Emperor Charles V and King Ferdinand into awarding him a noble title when they visited for the Diet of Augsburg.

As they do today, appearances played an important role in courtship as well. As a young man looking for a wife in a city overrun with young, unmarried male apprentices and journeymen, Matthäus carried heart-shaped purses in green and red—the colors of hope and desire. He captioned one splendid outfit: “All of this to please a beautiful person.” Following fashion also provided a hobby for all those lonely young men, who generally married late, once they had finished their vocational training, and thus had leisure time, money, and energy to expend on dressing up. It’s no coincidence that “urban young men” were the “drivers of innovative Renaissance fashion,” as Rublack points out. Several of the images in the book record what Matthaüs wore to the weddings of close friends (often matching his attire to that of other members of the bridal party) during his long bachelorhood.

The Klaidungsbüchlein effectively documents most of the rest of Matthaüs’s life. After he got married, his whole wardrobe faded to blacks and browns, and the gaps between images became longer. He grew a beard—a sign of maturity and masculinity—and traded his ornate, form-fitting doublets and hose for long, formal, fur-lined gowns. “This is when I began to be fat and round,” he notes despondently. Then in 1547, he suffered a stroke (“God’s mightiness hit me”), and managed to commission a portrait during his convalescence. Today, this rare Renaissance depiction of an invalid is one of the best known images in the Klaidungsbüchlein. But this is one of the last entries in the book. In the final image, he is a gray-bearded old man, dressed in mourning for his employer’s 1560 funeral. It might as well have been his own funeral: Matthäus lived another 14 years without commissioning a single portrait.

Matthäus’s preoccupation with fashion had always gone hand in hand with a keen sense of temporality and, by extension, mortality. Like his expanding waistline or recurring birthday—both of which he tracked with obsessive and, for his time, unusual assiduity—fashion, which seemed to change “day-by-day,” was a marker of the passage of time; “a vanishing moment of creativity and pleasure,” in Rublack’s phrase. One portrait depicts him with an eight-minute hourglass hanging from his belt. Another jaunty outfit is captioned: “On the 20th August, 1535, when people in Augsburg began to die. 38½ years old.”