" 'That Smile of Parmenides Made Me Think.' " The Griffin 5, no. 2 (February 1956). Also published as "The Smile of Parmenides: George Santayana in his Letters" in Encounter, December 1956: 30-37.

Excerpt:

One doesn’t have to read very far in Santayana s letters to become aware that it might be very hard to like this man–that, indeed, it might be remarkably easy to dislike him. And there is no point in struggling against the adverse feeling. The right thing to do is to recognize it, to admit it into consciousness, and to establish it beside that other awareness, which should come as early and which should be the stronger of the two–that Santayana was one of the most remarkable men of our time and that his letters are of classic importance.

Online:
Google Books - essay published in The Moral Obligation to be Intelligent
Unz.org - full text in Encounter