Change of self is loss of self, according to the traditional Greek attitude. Categorized as madness, it is held to be an unquestionable evil. Sokrates does not agree:
I must say this story [logos] is not true, the story that a nonlover should be gratified in preference to a lover on the grounds that the latter is mad while the former is sane. Now, if it were a simple fact that madness [mania] is evil, the story would be fine. But the fact is, the greatest of good things come to us though madness when it is conferred as a gift of the gods. (Plato’s Phaedrus, 244a)
Sokrates’ central argument, as he goes on to reevaluate madness, is that you keep your mind to yourself at the cost of closing out the gods. Truly good and indeed divine things are alive and active outside you and should be let in to work their changes. Such incursions formally instruct and enrich our lives in society; no prophet or healer or poet could practice his art if he did not lose his mind, Sokrates says (244a-45). Madness is the instrument of such intelligence. More to the point, erotic mania is a valuable thing in private life. It puts wings on your soul.