164 A. BAIN :

and reproduction of images, another term is desirable. In other words, the process" of converting the Sensation, or primary Impression, into the Idea, supposes the very same psychical force as that expressed by the law of Contiguity. III. Is Contrast to be regarded as a distinct and indepen- dent law of Association ? Contrast is a comparatively rare and exceptional bond of re- production. We cannot make six transitions of thought with- out involving the other two laws Contiguity and Similarity, but we maybe hours and days without acting upon Contrast. Hamilton and others, including Lotze, regard the relation of contrariety or contrast as equivalent to correlative parts of the same whole. A much bolder use of this explanation is made in dealing with the question next to be considered, and I do not discuss it here. I merely remark that while co-relatives, as light and dark, up and down, virtue and vice, readily suggest each other, I feel no difficulty in referring the process to the other laws of the mind. Lazarus suggests conjointly Dives, Abraham's bosom, and the place of in- sufferable heat ; and though one of the three links is of the nature of a contrast, yet in that too probably Contiguity is the operative resuscitating bond. IV. Whether Contiguity and Similarity may be reduced to one statement ? This is a far more serious consideration. Various attempts have been made to merge the two in a single principle. Hamilton, in the Reid, refutes some of these attempts, and affirms as ultimate the two principles- Repetition, under which he places Similarity, and Redintegra- tion. In the Metaphysics (Lect. xxxi.) he holds that the two laws of Simultaneity and Affinity are carried up into unity, in the higher law of Redintegration or Totality. According to Lotze, Similarity and Contrast are associa- tions of impressions that are either parts of a simultaneous whole or parts of a successive whole. So that with him, as with Hamilton (in the Metaphysics), the concurrence of parts of the same whole is the ruling principle of reproduction, explaining alike Contiguity, Similarity and Contrast. I must, therefore, make some remarks upon the method of regarding the entire compass of Association as the revival of a whole or totality on the presentation of some part of that whole. Such cases no doubt exist. After we have been familiarised with any complicated object, made up of definite parts, as an animal body, or a machine, when we