Socrates' “strangeness” is the keynote of Alcibiades' speech about him in the Symposium. The talk starts on that note (215A); and reverts to it near the end:

This book is for readers of Plato's earlier dialogues who have felt this strangeness, have asked themselves what to make of it, have pondered answers to its enigmas, and are willing to work their way through yet another. What I offer should not distract them from their encounter with the Socrates who lives in Plato's text. It should take them back there for a closer look.

The book has been a long time in the making. It started with a non-start. A stroke of luck in 1953 had assured me of a year entirely free from teaching. I had gone to the Institute for Advanced Study at Princeton to work on Plato's philosophy, uncommitted as to how I would proceed. Harold Cherniss, the great scholar in my field there, declined to give advice – how like Socrates he was in this. Left to my own devices, I cut the project in half, allocating the whole of that year to a study of Plato's Socratic dialogues.