  For Spinoza, as for Descartes, the metaphysical commitment to substance underwrote a rationalist epistemology that strongly privileges reason and intuition over sensation and imagination. The distinctive character of Spinoza’s epistemological rationalism is rooted in his principle that “the order and connection of ideas is the order and connection of things”. For Descartes, the mind and the body are, though intimately connected, radically heterogeneous.  How it is that the mind comes to know things about the physical world therefore remains, despite his best efforts, a somewhat murky business.  By rejecting the substantiality of both minds and bodies, and by regarding them both as modes of a single substance, Spinoza obviated this difficulty. For Spinoza, the mind and the body are the very same thing conceived in two different ways. Persistent clusters of qualities in space are bodies. The ideas—or, in Descartes’s terminology, the objective reality—of these bodies are minds. Just as a single body has a corresponding objective reality, so collections of bodies characterized by various relations also have a corresponding objective reality with isomorphic parts and relations. Since there is no gap between minds and bodies, there is therefore no difficulty in principle in perceiving the physical world. On Spinoza’s account, we perceive the physical world in two ways—(1) by perceiving the actions of our own bodies, and (2) by perceiving the effects of other bodies on ours. Thus, when one’s body runs, the correlative ideas are in one’s mind. Likewise, when someone steps on one’s toe, the physical effects on the toe likewise have their counterparts in the mind’s ideas.