In fact, whatever exists in the universe, in essence, in appearance, in the imagination, the painter has first in his mind and then in his hands ... it lies in his power to create them . . .

The merit of painting lies in the exactness of reproduction. Painting is a science and all sciences are based on mathematics. No human inquiry can be a science unless it pursues its path through mathematical exposition and demonstration.

It vexes me greatly that having to earn my living has forced me to interrupt the work and to attend to small matters.

The first of all simple colours is White ... We shall set down White for the representative of light, without which no colour can be seen; Yellow for the earth; Green for water; Blue for air; Red for fire; and Black for total darkness.

Whoever despises the high wisdom of mathematics nourishes himself on delusion and will never still the sophistic sciences whose only product is an eternal uproar.

Ask advice of him who governs himself well.

All our knowledge originates in opinion.