“Then love, and desire, and friendship would appear to be of the natural or congenial. Such, Lysis and Menexenus, is the inference.”
Socrates tentatively suggests that attachment may arise from an affinity between people, after reasoning about what desire lacks. He and his companions immediately test—and ultimately fail to settle—this proposal; the sentence is a provisional inference, not Plato’s final definition of love or friendship.
Source details
Lysis, around Stephanus 221e, Socrates addressing Lysis and Menexenus while exploring desire, affinity and friendship. Benjamin Jowett English, Project Gutenberg #1579. The dialogue goes on to challenge whether the congenial is simply the like and ends without reaching a settled definition; do not present the tentative argument as an unconditional fact.