a profound difference between the analogues: the exactest similarity between A and B requires that A and B should be different individuals. Likeness is often presented to us as the truth underlying what we hastily take to be identity of kind, and the correlative unlikeness which together with it constitutes the relation of analogy as the truth underlying difference of kind.
Is the relation between acting and knowing one of analogy? Certainly the points of resemblance which exist between the man of action and the man of thought, the doer and the thinker, the deed and the thought, are numerous and striking. We come not easily to an end of them. Nor do they lie merely on the surface: they constitute a profound homology of structure. On this rests the possibility of their conjunction and co-operation. That is what, when we recognize it, makes us call them both psychic or spiritual, or even rational. Yet there remains their difference, and just that difference which is required by their character as analogues of one another. This difference in the general case of analogy we express by calling it a difference of the sphere of application as opposed to the sameness of the principle, a difference of the medium as opposed to the identity of the function, or most simply as a difference of the matter or materials as opposed to the homology of the plan, structure, or form. Can we apply this to the case before us? What are the materials, the substance, out of which acting and knowing are severally but similarly built up? The only answer can be, out of acts and thoughts (knowledges) of a more elementary kind: descend in analysis below these, and again you find the same. The difference between them is endless or ultimate. Even in their most inchoate forms the one preserves its difference from the other.
