POSTULATE

, a demand, petition, or a problem of so obvious a nature, as to need neither demonstration, nor explication, to render it either more plain or certain. This definition will nearly agree also to an axiom, which is a self-evident theorem, as a Postulate is a self-evident problem.

Euclid lays down these three Postulates in his Elements; viz, 1st, That from one point to another a line can be drawn. 2d, That a right line can be produced out at pleasure. 3d, That with any centre and radius a circle may be described.

As to axioms, he has a great number; as, That two things which are equal to one and the same thing, are equal to each other, &c.