May not the truth be that, as we were saying, desire is the cause of friendship; for that which desires is dear to that which is desired at the time of desire? And may not the other theory have been just a long story about nothing?
This quote sums up the Lysis as well as any other. The conversation has ranged through a number of possibilities for the cause of friendship (the beloved, the lover, the good, the like, the unlike, and even evil), and found none of them to be satisfying. By the end of the dialogue only a few pages after this quote, Socrates will simply give up the chase: "I know not what remains to be said." There is a sense, in the Lysis, that desire is uncontrollable, or rather just barely controllable with such slippery tools as emotional deduction, poetic inspiration, and argumentative intoxication; in any case, philosophical analysis doesn't seem to help much. Though a number of important abstract ideas are raised over the course of the conversation, it is notable that the last real resting place of the argument is simply that desire, somehow or other, causes friendship.
The "other theory" that Socrates suspects of being "a long story about nothing" is in fact the longest analysis in the dialogue, and it yields the most complex and unwieldy argument: friendship depends on that which is neither good nor bad befriending the good in order to avoid evil. Besides its awkwardness, this theory has the perverse consequence of positing evil as the immediate cause of friendship. Socrates rejects this argument by freeing desire from any association with evil. Desire, he argues, is in itself neither good nor bad; thus, even if all evil were eliminated, desire (and therefore friendship) would still be around. In the end, then, we don't learn much about desire from the philosophy of the Lysis, even though desire marks the final resting place of the troubled discussion. Desire remains an enigma, a necessary factor that cannot be described in its qualities or its cause beyond an assertion that it is, by itself, neither good nor evil. In closing, we might note that significantly more can be learned about desire from the characters and behavior of the participants in the dialogue than from the philosophical content of the dialogue.