An atmosphere of authority prevails as watercolorist O'Hara takes to type and the writing of a book about his art. He composes from the paper up, for the novice--with information on materials, basic techniques, color and light, light and shadow, corrections. For the more advanced, more advanced techniques--wet-blending for soft transitions, calligraphy, unpainted intervals are applied, with the advice not to wait too long to attempt them. Mr. O'Hara discusses opaque watercolors and related mediums (gouache, casein, polymer, collage); techniques relating to special subjects (birds in flight, a forest, crowds, sea and surf, portraits, etc.); composition, design and related matter (how to make space recede, scale, balance, rhythm, restraint). He offers a word on abstract and nonobjective painting, on a variety of approaches to encourage imagination, and on exhibiting.