Up to this point the imagination has been treated analytically only. This process alone would give us but a very imperfect idea of its essentially concrete and lively nature were we to stop here. So this part continues the subject in another shape. I shall attempt to follow the imagination in its ascending development from the lowest to the most complex forms, from the animal to the human infant, to primitive man, thence to the highest modes of invention. It will thus be exhibited in the inexhaustible variety of its manifestations which the abstract and simplifying process of analysis does not permit us to suspect. I I shall not dwell at length on the imagination of animals, not only because the question is much involved but also because it is hardly liable to a positive solution. Even eliminating mere anecdotes and doubtful observations, there is no lack of verified and authentic material, but it still remains to interpret them. As soon as we begin to conjecture we know how difficult it is to divest ourselves of all anthropomorphism. The question has been formulated, even if not treated, with much system by Romanes in his _Mental Evolution in Animals_.[35] Taking "imagination" in its broadest sense, he recognizes four stages: 1. Provoked revival of images. For example, the sight of an orange reminds one of its taste. This is a low form of memory, resting on association by contiguity. It is met with very far down in the animal scale, and the author furnishes abundant proof of it. 2. Spontaneous revival. An object present calls up an absent object. This is a higher form of memory, frequent in ants, bees, wasps, etc., which fact explains the mistrustful sagacity of wild animals. At night, the distant baying of a hound stops the fox in his course, because all the dangers he has undergone are represented in his mind. These two stages do not go beyond memory pure and simple, i.e., reproductive imagination. The other two constitute the higher imagination. 3. The capacity of associating absent images, without suggestion derived from without, through an internal working of the mind. It is the lower and primitive form of the creative imagination, which may be called a passive synthesis. In order to establish its existence, Romanes reminds us that dreams have been proven in dogs, horses, and a large number of birds; that certain animals, especially in anger, seem to be subject to delusions and pursued by phantoms; and lastly, that in some there is produced a condition resembling nostalgia, expressing itself in a violent desire to return to former haunts, or in a wasting away resulting from the absence of accustomed persons and things. All these facts, especially the latter, can hardly be explained without a vivid recollection of the images of previous life.