I don't find much to disagree with in what Don has written, and I think that those who imagine a necessary relation between materialism and nihilism are never going to be impressed by any amount of space we put between Epicurus and Democritus on this point.
QuoteSo when it is said that "everything else is merely THOUGHT to exist" or "exists by convention" (which implies "consensus?)
I certainly don't think this is quite what Democritus was driving at. Merely that these other aspects of nature are contingent on or emergent from matter. "Sweet" exists at the point of interaction between sense receptors on the tongue and one of a number of chemical compounds. When we say "it's sweet", I think what we really mean is "it tastes sweet [to me]". At this point we ask not the philosophical question but the Darwinian one; why do our bodies register sweetness as a reward?
And maybe now is a good time to remind everyone about the great and glorious Mochus! This Mochus, the alleged father of ancient atomism, was considered by several early English scientists to have been one and the same with Moses himself; and by this circuitous route they make God out to be the father of Atomism, and they further connect the Greek word atom with the Hebrew name Adam, the "first beginnings". Does atomism lead to nihilism or not? Per usual, they are trying to have it both ways.