Themes in Phaedrus

It seems to me that there is a strong threefold analogy in the Phaedrus. First, Socrates examines the idea of paederastic relationships without love. Then, he examines the idea of rhetoric without truth, and finally, he examines the idea of writing without critical thought. Love, truth, and critical thought all seem to provide vitality and meaning, without which the activities listed regress to nonsense. Any thoughts?