What is philosophy? That’s a good question—not because there’s no answer, but because what’s involved in posing it points up something essential to philosophy. In the Treatise on the Emendation of the Intellect, Spinoza sets out what’s required by a definition. A circle, a typical definition might run, is a figure in which all lines drawn from the center to the circumference are equal. The problem with this definition, what makes it merely verbal, is that it defines a circle by way of one of its properties, not by way of its essence. Definition, for Spinoza, gets at the essence (from which all properties follow): A complete definition demonstrates how what it defines comes about. The definition of a circle as a figure that is described by any line of which one end is fixed and the other movable, as one commentator has pointed out, “literally generates the circle by providing a procedure whereby we ‘make’ the thing to be defined.” Philosophy is defined by what takes place in the question of philosophy itself. What Auden said of poetry could also be said of philosophy: it makes nothing happen. *Nothing* happens, or nothing *happens*—and in the space of the same few words both can. Philosophy operates that displacement and is defined by it: “what is *philosophy*?” become “*what is* philosophy?”—the question persists, but everything has changed.