Following on from Proust On Memes:

A powerful idea communicates some of its power to the man who contradicts it. Partaking of the universal community of minds, it infiltrates, grafts itself on to, the mind of him whom it refutes,among other contiguous ideas, with the aid of which, counter attacking, he complements and corrects it; so that the final verdict is always to some extent the work of both parties to a discussion. It is to ideas which are not, strictly speaking, ideas at all,to ideas which, based on nothing, can find no foothold, no fraternal echo in the mind of the adversary, that the latter,grappling as it were with thin air, can find no word to say in answer.