  It is on the face of it extremely implausible to deny change, but extreme implausibility has not always deterred philosophers. The Eleatics (C5th BCE), particularly Parmenides, appear to have been the first to do so. Parmenides maintained that whatever one speaks about or thinks about must in some sense exist; if it did not exist then it is nothing, so one would be speaking or thinking about nothing, which would be empty. From this thesis, it is deduced that the existing thing cannot have come into existence, because to say that it could would be to speak of a time when it did not exist. By similar reasoning, existing things are eternal because they cannot go out of existence. It is now a small step to conclude that change is an illusion, on the grounds that a change in a thing implies that there was a time when the thing-as-changed did not exist. However, this argument is not persuasive: the premiss that the non-existent cannot be thought or spoken about is dubious.