
The Metaphysical Elements of Ethics is classic philosophy text by the German philosopher Immanuel Kant that imcludes this passage: "If there exists on any subject a philosophy (that is, a system of rational knowledge based on concepts), then there must also be for this philosophy...

If there exists on any subject a philosophy (that is, a system of rational knowledge based on concepts), then there must also be for this philosophy a system of pure rational concepts, independent of any condition of intuition, in other words, a metaphysic. It...