ABSTRACT
Quantitative Reasoning involves, with more or less constancy, the three ideas, coextension, coexistence and connature: or to speak less accurately, but more comprehensibly—sameness in the quantity of space occupied; sameness in the time of presentation to consciousness ; and sameness in kind. The germ out of which Quantitative Reasoning grows— the simple intuition of the equality of two magnitudes, necessarily involves all these: seeing that there can be no comparison between them unless they are of the same kind; and their coextension cannot be perceived unless they are coexistent. The fact that perfect quantitative reasoning deals exclusively with intuitions of the coextension of coexistent magnitudes that are connatural, will be most clearly seen when it is remarked that the intuitions of coextension, of coexistence, and of connature, are the sole perfectly, definite intuitions of which we are capable.
