Now, because rational thinking is perfected through a scientific habit, there are different sciences corresponding to the different orders that it is the office of reason to consider. The philosophy of nature is concerned with the order of things that human reason examines but does not make, so that we also include both mathematics and metaphysics under the philosophy of nature. The order that reason by its act of thinking produces in its own act pertains to rational philosophy, which is concerned with the order of the parts of discourse to each other and the order of principles to conclusions. The order of voluntary actions belongs to the consideration of moral philosophy. And the order that reason by its thinking produces in external things, made through human reason pertains to the mechanical arts.

–St. Thomas Aquinas (Commentary on Aristotle's Ethics, I lect. 1)