BONNARD by Nicholas Watkins. (Phaidon: $49.95) Pierre Bonnard (1867-1947) began his career as a graphic artist, creating many memorable and famous posters and advertisements like the one above ("La Petite Blanchisseuse," 1896), or the well-known "France-Champagne" (with poem), or "Femmes au jardin," 1891 (with text, above). But something snapped. In 1900 he began spending more and more time in the country, with Marthe, his companion and later wife. He painted rooms, and views from rooms, and cupboards, and Marthe. Marthe in the bath, Marthe getting into the bath, Marthe sitting at the table. The subjects, like his daily diary entries, are simple: "Beau," "Beau Temps," "Pluie le Matin," but his colors are warm and explosive and harmonious. When you become familiar with his paintings, you think of his colors when you look at rooms. More than anything, you want to live in them and look out.