The view Berkeley defends in these passages has recognizable antecedents in Locke’s Essay Concerning Human Understanding (1690: Book II, Chap. 9, §§8–10). There Locke maintained that the immediate objects of sight are “flat” or lack outward depth; that sight must be coordinated with touch in order to mediate judgments concerning the disposition of objects in three-dimensional space; and that visible ideas “excite” in the mind movement-based ideas of distance through an associative process akin to that whereby words suggest their meanings: the process is 