  While several reports of Democritus' view, apparently direct quotations, mention exclusively sensible qualities as being unreal, a report of Plutarch includes in the list of things that exist only by convention the notion of ‘combination’ or sunkrisis.  If this report is genuinely Democritean, it would broaden the scope of the claim considerably: the idea that any combination—by which he presumably means any cluster of atoms—is ‘unreal’ or merely ‘conventional’ suggests that Democritus is drawing a more radical distinction than that between sensible and nonsensible qualities.  The implication would be that anything perceived, because it is a perception of combinations of atoms and not atoms themselves, would count as ‘unreal,’ not merely the qualia experienced by means of individual sense organs.  One report indeed attributes to Democritus a denial that two things could become one, or vice versa (DK 68A42), thus suggesting that combinations are regarded as conventional.