Memory exercised in a particular way is a natural gift of poetic genius. The poet above all else, is a person who never forgets certain sense impressions which he has experienced and which he can relive again as though with all their original freshness.
The lunatic is all idée fixe, and whatever he comes across confirms his lunacy. You can tell him by the liberties he takes with common sense, by his flashes of inspiration, and by the fact that sooner or later he brings up the Templars.