Whatever the reason for the change may have been, it would be flying in the face of current usage (and indeed of the usage of the last three or four hundred years) to stipulate that the subject-matter of metaphysics was to be the subject-matter of Aristotle's Metaphysics. It would, moreover, fly in the face of the fact that there are and have been paradigmatic metaphysicians who deny that there are first causes—this denial is certainly a metaphysical thesis in the current sense—others who insist that everything changes (Heraclitus and any more recent philosopher who is both a materialist and a nominalist), and others still (Parmenides and Zeno) who deny that there is a special class of objects that do not change. In trying to characterize metaphysics as a field, the best starting point is to consider the myriad topics traditionally assigned to it.