INTUI'TION, noun [Latin intuitus, intueor; in and tueor.]

A looking on; a sight or view; but restricted to mental view or perception. Particularly and appropriately, the act by which the mind perceives the agreement or disagreement of two ideas, or the truth of things, immediately, or the moment they are presented, without the intervention of other ideas, or without reasoning and deduction.

We know by intuition that a part is less than the whole.