If you condemn painting, which is the only imitator of all visible works of nature, you will certainly despise a subtle invention which brings philosophy and subtle speculation to the consideration of the nature of all forms — seas and plains, trees, animals, plants and flowers — which are surrounded by shade and light. And this is true knowledge and the legitimate issue of nature; for painting is born of nature — or, to speak more correctly, we will say it is the grandchild of nature; for all visible things are produced by nature, and these her children have given birth to painting. Hence we may justly call it the grandchild of nature and related to God.

The Notebooks of Leonardo da Vinci (Richter, 1888) - IX The Practice of Painting