It reflects no great honor on a painter to be able to execute only one thing well -- such as a head, an academy figure, or draperies, animals, landscapes, or the like -- in other words, confining himself to some particular object of study. This is so because there is scarcely a person so devoid of genius as to fail of success if he applies himself earnestly to one branch of study and practices it continually.

...The world wouldn't be the world, without trouble.

O time! swift devourer of all created things!

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.

Life well spent is long.

The lie is so vile, that even if it were in speaking well of godly things, it would take off something from God's grace; and Truth is so excellent, that if it praises but small things they become noble.

Many have made a trade of delusions and false miracles, deceiving the stupid multitudes.