    The most ubiquitous mental power is that of conception. Our suite of intellectual faculties supports a wide variety of mental events. Acts of conceiving are embedded in most of them. Whether judging that there is a tree before me, imagining there is a tree before me, or reasoning to a generalization that all trees have roots, these mental events employ the faculty of conception. It is in virtue of conception that the first of these mental states is about the proposition there is a tree before me; that the second mental state takes as its object a non-existent tree; and that the third uses a general conception of ‘tree’. The Way of Ideas teaches, wrongly, that acts of perception temporally begin with an act of simple apprehension “and that after we have got simple apprehensions, by comparing them together, we perceive agreements or disagreements between them,” but, Reid continues, “this appears to me to be all fiction, without any foundation in nature” (IHM 2.4, 29). Instead, simple apprehension—the basic form of conception—is bundled within typical acts of perception. The model of conception received from the Way of Ideas marks its first long step into two types of skepticism.