The triplet, like some other literary forms, had an origin, a period of growth, a maturity, and then an end. The triplet was an offspring of the pentameter couplet, but developed in its own way at its own rate. When the couplet was loose, open, and unpolished, there was little need for further variety, and poets wrote few triplets. When the couplet became tight, closed, and highly polished, as it did with Pope, the triplet was considered a violation of the rules. It was, consequently, only in the short period just before the apex of the couplet that the triplet could flourish: the period of John Dryden.