Ill-digested principles are, if anything, worse than ill-digested food, for the latter harms the body and there is cure for it, whereas the former ruins the soul and there is no cure for it.
But like infection is the petty thought: it creeps and hides, and wants to be nowhere--until the whole body is decayed and withered by the petty infection... Thus spoke Zarathustra.
The fury of a demon instantly possessed me. I knew myself no longer. My original soul seemed, at once, to take its flight from my body; and a more than fiendish malevolence, gin-nurtured, thrilled every fibre of my frame.