 However, in the present context his arguments are chiefly interesting not so much for their elaboration of associationism, as for the light they throw on the development of Scottish philosophy in the nineteenth century. One point in particular seems to me illuminating. In the dispute between Reid and Hume with respect to the operations of the mind one of the fundamental points of difference is this. Reid is trying, in the main, to establish basic principles of the mind's operation which will vindicate its rationality, and hence avoid the depths of skepticism into which Hume's account forces it. Hume, on the contrary, declares that “reason is nothing but a wonderful and unintelligible instinct in our souls which carries us along a certain train of ideas…[and that this] habit is nothing but one of the principles of nature, and derives all its force from that origin” (Hume 1888, 179), Reid's purpose is precisely to show that the basic operations of the mind are more than psychological regularities. They are exercises of intelligibility. Now in terms of this difference, Bain is of Hume's persuasion. This is revealed not merely in his striking deployment of decidedly Humean terminology when, for instance, he contrasts the perception and the memory of a thing in terms of “vividness” (Bain 1903, 42). It is even more evident when he asserts that “The flow of representations in dreaming and madness offers the best field of observation for the study of associations as such” (ibid., 45).