 Locke viewed attention as an explanatorily slight phenomenon—a mode of thought that is not in need of much explanation, nor capable of providing much. Theories of attention moved away from that view over the course of the eighteenth century. Attention was increasingly treated as a phenomenon with explanatory work to do, and so as a phenomenon for which a substantive independent theory needed to be given. The attempt to provide such a theory got properly underway in 1738, when Christian Wolff’s textbook on psychology was the first to devote a whole chapter to the topic of attention (see Hatfield, 1995, for an excellent discussion).