After escaping the reach of Michelangelo’s marble hammer—Sofia was nowhere to be seen—I jogged across town to Santa Maria Novella, the Dominican church with the beautiful facade completed by Leon Battista Alberti. Usually, I sit down to draw the facade of that church—the balanced and harmonious geometric shapes of white, green, and black marble give me comfort—but on that day, I didn’t even pause out front. I also didn’t stop inside to take in the high nave, slender columns, or graceful black-and-white striped arches. No. I went directly to Masaccio’s fresco, Holy Trinity. It’s my favorite painting in all of Florence: Christ hanging on the cross, God the Father standing behind, white dove of the Holy Spirit fluttering between them, while Mary, John, and two patrons flank either side, all depicted in a painted chapel that looks so real you might think that Masaccio had cut an actual room into the wall of that church. The perspective is incredible, every element—down to the nails in Christ’s hands—receding toward a single vanishing point. Before Masaccio—I love that nickname, “Messy Tom,” don’t you?—paintings had been flat, lifeless things, but he showed us how to transform a flat picture surface into real depth.

That fresco isn’t perfect. Far from it. But you know what it is, don’t you? It’s our map to perfection. It shows us what to aim for: perfect composition, perfect perspective, perfect color, perfect shadow, perfect light, perfect figures, perfect draperies, perfect balance, perfect harmony. Back then, it had already been eighty years since Masaccio painted that fresco and showed us the way to perfection, but not one painter had achieved it. Not yet. On the bottom of that fresco, Masaccio had painted a skeleton lying on top of a sarcophagus, inscribed with a warning about the brevity of life: I once was what you are, and what I am you will be also. Masaccio was young when he painted Holy Trinity—not much older than I was back then—and a few years later, at age 27, Messy Tom was dead.

I knelt in front of that painting and smoothed out a sketch of Michelangelo’s cartoon that I’d managed to save: a quick copy of pulsating figures. Michelangelo was not aiming for perfection, but he had given me one of the keys to achieving it. Masaccio had tried—through shadow, curve, and perspective—to create realistic figures, but he’d fallen short. Michelangelo, on the other hand . . . His figures are too twisting, straining, and agonizing to be perfect, but they are sculptural and more real than anything I’d ever seen captured on a flat surface. In order to create a perfect painting, I was going to have to learn to paint figures as real and round as his.