  Spinoza is not the first to furnish his metaphysics with attributes and in that he is following a very long tradition. He is, though, mostly influenced by Descartes, and in some ways is trying to keep with Descartes’ notion of “attribute.” It therefore will be useful to look back and get a sense of what Descartes had in mind and thus get a preliminary grasp (which will be revised) of what Spinoza means by “attribute.” Descartes states in the Principles of Philosophy that attributes are the essence of a thing, so the essence of mind is thought or thinking, and the essence of body is to be extended (Principles, I, §53, CSM, I, p. 210, AT 25). To see why this is so, it is worth revisiting the first and second Meditations, even if very briefly. Let us begin with body and Extension. To understand the essence of body, we can look to the famous wax example in Meditation Two (CSM, II, p. 20–21, AT 30–32). While sitting by the fireplace, Descartes inspects a piece of wax and asks himself what he knows of the wax. He begins by listing all the sensory properties of the wax: it is white, has a certain smell, makes a certain sound when one raps it with one’s finger, is hard, and has a certain taste. After listing all its sensory properties, he then places the piece of wax by the fire and sees how it loses all those properties: it changes color, smell, texture, taste, etc. Descartes concludes, among other things, that the essence of the wax, insofar as it is a body, is that it is extended in length, breadth, and depth since that is the only thing that remains constant about the wax. In this respect, the piece of wax is no different from any other body—that is, its essence is to be extended. Extension, then, according to Descartes, is the essence of body. In the Meditations we also, famously, come to recognize our own essence as thinking things. We realize this by recognizing that we cannot doubt that we are doubting while doubting. Furthermore, we realize that doubting in this sense is no different from understanding, affirming, denying, willing, unwilling, imagining, and having sense perceptions (seeming to see, etc.) (CSM, II, p. 19, AT 28). Descartes then reaches the conclusion that the essence of the mind is Thought. For these reasons, Descartes claims that Thought and Extension are the principal attributes of mind and body and that they are “really distinct”, that is, they exist independently one from the other.[4]  It is important to note that for Descartes, any created substance has only one principal attribute, as opposed to God who has infinite attributes.