Instant

(in's tant.) [L. in stans.] The smallest perceptible portion of time; or that in which we perceive no succe ion. Schoolmen distinguish three kinds of instant: the temporary, a portion of time preceding another; the natural, which is a mere priority of nature; and the rational, which is not a real point, but one which the understanding supposes to have existed before another, from the nature of things, which cause it to be looked on as pre-existing. [s. 487]