The Idiot Part 2 Chapter 5 Page 8

Therefore they are not really a higher kind of life, but a lower.” This reasoning, however, seemed to end in a paradox, and lead to the further consideration: — ”What matter though it be only disease, an abnormal tension of the brain, if when I recall and analyze the moment, it seems to have been one of harmony and beauty in the highest degree — an instant of deepest sensation, overflowing with unbounded joy and rapture, ecstatic devotion, and completest life?” Vague though this sounds, it was perfectly comprehensible to Muishkin, though he knew that it was but a feeble expression of his sensations.

That there was, indeed, beauty and harmony in those abnormal moments, that they really contained the highest synthesis of life, he could not doubt, nor even admit the possibility of doubt.