 Spinoza is, in a fairly obvious way, a champion of a mathematical approach to understanding the physical world. But Spinoza's mathematical model is Euclidean geometry, and this is not a domain of mathematics that deals with quantities as measurable. And indeed, there is strong evidence that Spinoza thought that a proper understanding of physical nature can never be expressed in terms of measurable quantities. For measure, both of spatial extent and temporal duration, is a mere aid to the imagination, and not a means of intellectually understanding. In Letter 12 to Meyer, Spinoza distinguishes two ways of conceiving quantity. One is abstract and superficial, as we have it is sensation and imagination; on this conception quantities can be finite, divisible, and composed of parts. The other is through the intellect's grasp of substance in which “we apprehend the thing as it is in itself”; on this conception, quantity is infinite, indivisible, and a unity. Spinoza goes on to elaborate how measure of spatial and temporal quantity derives from the abstract, superficial conception of quantity, and leads to nothing but confusion in the attempt to understand physical nature. His discussion is worth quoting at length.