The Pluralist school was a school of pre-Socratic philosophers who attempted to reconcile Parmenides' rejection of change with the apparently changing world of sense experience, it can also be said to have included which philosopher who was the earliest Greek to develop the theory of atomism—the idea that everything is composed entirely of various imperishable, indivisible elements called atoms. Leucippus often appears as the master to his pupil Democritus, a philosopher also touted as the originator of the atomic theory?