We have said that the painter represents or suggests some form in nature. Sometimes he represents the actual appearance of nature, as when he paints a portrait or a landscape. At other times he suggests the possible appearance of things, which he has never seen but only imagines, as the old Italian painters did when they made pictures of St. George, killing the dragon, or of Christ in the manger, with a choir of angels hovering above. They had never seen a dragon, but from their study of the lizard, which in hot countries like Italy may constantly be seen basking on the hot rocks or darting away at your approach, they imagined a form and painted it so that it suggests an actual creature. So, for their angels, they studied the forms and movement of children, as they ran and played, with hair and skirts streaming in the wind; also the wings and the flight of birds, and the appearance of the sky. Nature was, as it still remains, the artist’s teacher. Just in what way he learns of her and uses her lessons, I am going to try and show you. But first let me remind you that nature and art, though so close together that I have called them twin sisters, are quite separate. I do so because many people confuse them together. Frequently you will hear a person say of some view of nature that it is “beautiful as a picture.” Well, very likely it is, but as we shall see, not in the same way. Or some one will exclaim, as he stands in front of a picture, “It looks like nature.” So it does; and yet it is not really like nature. Why both these remarks are in a small way true, but in the big sense not true, we shall discover, I hope, presently. Meanwhile, suppose we lay the book aside and look out of the window.