From Various Outcomes of the Same Plan:
Now I say that not only in medicine but in many more certain arts Fortune has a large part. Poetic sallies, which transport their author and ravish him out of himself, why shall we not attribute them to his good luck? He himself confesses that they surpass his ability and strength, and acknowledges that they come from something other than himself and that he does not have them at all in his power, any more than orators say they have in theirs those extraordinary impulses and agitations that push them beyond their plan. It is the same thing with painting: sometimes there escape from the painter’s hand touches so surpassing his conception and his knowledge as to arouse his wonder and astonishment. But Fortune shows still more evidently the part she has in all these works by the graces and beauties that are found in them, not only without the workman’s intention, but even without his knowledge. An able reader often discovers in other men’s writings perfections beyond those that the author put in or perceived, and lends them richer meanings and aspects.