Human beings fear difference, Lilith had told him once. Oankali crave difference. Humans persecute their different ones, yet they need them to give themselves definition and status. Oankali seek difference and collect it. They need it to keep themselves from stagnation and overspecialization. If you don't understand this, you will. You'll probably find both tendencies surfacing in your own behavior. And she had put her hand on his hair. When you feel a conflict, try to go the Oankali way. Embrace difference.

Part II Phoenix chapter 4 (p. 329) - Adulthood Rites (1988)