 Much of the technical language of Part One is, to all appearances, right out of Descartes. But even the most devoted Cartesian would have had a hard time understanding (and, certainly, accepting) the full import of propositions one through fifteen. What does it mean to say that God is substance and that everything else is “in” God? Is Spinoza saying that rocks, tables, chairs, birds, mountains, rivers and human beings are all properties of God, and hence can be predicated of God (just as one would say that the table “is red”)? It seems very odd to think that objects and individuals—what we ordinarily think of as independent “things”—are, in fact, merely properties of a thing, items that inhere in something else. Spinoza was sensitive to the strangeness of this kind of talk, not to mention the philosophical problems to which it gives rise. When a person feels pain, does it follow that the pain is ultimately just a property of God, and thus that God feels pain? All of this has given rise to a great deal of scholarly debate as to what Spinoza means by saying all things being modes of or “in” God. They may also explain why, as of Proposition Sixteen, there is a subtle but important shift in Spinoza’s language. God is now described not so much as the underlying substance of all things, but as the universal, immanent and sustaining cause of all that exists: “From the necessity of the divine nature there must follow infinitely many things in infinitely many modes, (i.e., everything that can fall under an infinite intellect)”.