Leonardo had almost no schooling and could barely read Latin or do long division. His genius was of the type we can understand, even take lessons from. It was based on skills we can aspire to improve in ourselves, such as curiosity and intense observation. He had an imagination so excitable that it flirted with the edges of fantasy, which is also something we can try to preserve in ourselves and indulge in our children.

An object will display the greatest difference of light and shade when it is seen in the strongest light. . . . But this should not be much used in painting, because the works would be crude and ungraceful. An object seen in a moderate light displays little difference in its light and shade, and this is the case towards evening or when the day is cloudy; works painted then are tender, and every kind of face becomes graceful. Thus, in everything extremes are to be avoided: Too much light gives crudeness; too little prevents our seeing.

I want it to be as beautiful as possible, even if it's inside the box. A great carpenter isn't going to use lousy wood for the back of a cabinet, even though nobody's going to see it.