nihil in intellectu nisi prius in sensu

(Latin, nothing in the intellect unless first in sense (the senses)) The guiding principle of empiricism, and accepted in some form by Aristotle, Aquinas, Locke, Berkeley, and Hume. Leibniz, however, added nisi intellectus ipse (except the intellect itself), opening the way to the view taken up by Kant, that the forms of reason form an innate structure conditioning the nature of experience itself.