Many of Leonardo da Vinci's paintings were portraits of nobles and famous figures. Though he was a gifted, brilliant genius, his habit of throwing his time and energy into every interest, then breaking appointments every few days, was unbearable. Financial disputes cropped up from time to time throughout his dazzling life, and even the Pope called him "a man who never finished what he started."
Pigments were expensive, especially ultramarine, which was even more precious than gold. It was rare even in Leonardo da Vinci's paintings, yet Vermeer loved to use it. But he did not paint famous people or nobles, only ordinary people. That was also the hallmark of genre painting: it recorded subjects and figures from social life, often trivial everyday matters. But was daily life worth depicting with ultramarine that cost as much as gold?
People tended to believe only major events needed recording. Take The Arnolfini Portrait: the male figure held the hand of his newlywed wife, while she lowered her head slightly and rested her left hand over her rounded belly, making her appear pregnant.
A mirror hung on the wall behind them, reflecting their backs as well as the painter himself and another person. That mirror was not the flat kind people commonly knew, but a convex mirror.
Perhaps due to technical limitations, most mirrors made during the Middle Ages were convex. Even in the sixteenth century, painters still painted self-portraits reflected in convex mirrors onto bulging wooden panels. The ceiling of the Sistine Chapel was not flat but curved. Even if Michelangelo finished his sketches on the ground and then transferred them upward, the figures would look unnatural if he failed to account for distortion caused by the curved surface.
In short, both Leonardo da Vinci and Michelangelo left behind vast quantities of