Conjuring up all sorts of hindrances, difficulties, and dangers is a modification of this castle building, and gives more play to the intellectual faculties as we weigh the varying possibilities of success or failure, develop the probable consequences of a proposed step, and try to find the best and easiest road to success. By such processes the crude picture is moulded into shape. Here, again, the capacity for illusion is of importance in connection with imaginative combination, since each possibility that is considered has the appearance of reality in its turn, but such mental activity is playful only when the combinations as such are enjoyable. Every creative artist, statesman, writer, or scholar must often work on an imaginative basis which he knows he can never verify. Many persons like to take, with the help of a Baedeker, long journeys which they can never hope to indulge in in any other way, and to solve complicated problems based on hypothetical games of chess. Leaving castle building, let us see what other forms of constructive fantasy can be practiced playfully. In speaking of illusions we have noticed the blending of memories with external phenomena, which is so conspicuous in child play and in æsthetic enjoyment. The process of “assimilation” which grounds playful self-deception is so closely related to constructive imagination that it is difficult to locate the boundary between them. The psychic process which transforms a splinter into a doll’s milk-bottle, a few chips stuck up into men and trees, a cloud[299] into the greatest variety of faces, animals, etc., which endows lifeless objects with our own spiritual capacities of desire, emotion, and temper—all this is synthetic activity which may quite as well be called assimilation as constructive imagination. Its pleasurable quality is inherent,[300] especially where a perfect imitation of reality would give us so little room for the exercise of imagination as to be on the whole less satisfactory.