A concept is the representation of an object (a thing or a state of things) in a general way. The general character is not due to a certain obscurity and vagueness, as in “general” sensible representations. It is due to the drawing out (abstraction) by the intellect of something that is common as such to several objects — a “whatness” or essence about the existence of which no affirmation at all is immediately made. Abstraction takes place in the “light” of the “active” intellect (intellectus agens) which manifests the intelligible element in the sensible thing present.

Thus the concept li…