Well, artists discovered the truth of this. Constable and Rousseau lead the way, and now it is the usual habit of the landscape artists to study nature as one studies the face and form, the expression and action of a friend. One cannot know a number of friends as intimately as one or two. So they have confined their pictures to the few and simple aspects of nature; one little fragment at a time, studied with loving intimacy and represented with the faithfulness of sincere and thorough knowledge. In doing so, they have learned like Johannes Vermeer and other Dutch artists of the Seventeenth Century, that much of the beauty and almost all the expression on the face of nature are due to the effects of natural light. Light has become the special study of the modern painters of the naturalistic landscape. And they have carried it further than the other artists did. Helped by the scientific men, who have examined into the color of light, the modern artist has found out how to represent a great variety of the effects of light: cool or warm light, the light at a particular hour of the day, at a particular season of the year, and in a particular kind of weather. In fact, the light that he represents in his pictures is a faithful rendering of some one of the countless conditions of natural light.