Also Sprach Zarathustra: But everything that suffereth wanteth to live, that it may become mature and lively and longing - longing for the further, the higher, the brighter. "I want heirs," so saith everything that suffereth, "I want children, I do not want MYSELF,"
Joy, however, doth not want heirs, it doth not want children, - joy wanteth itself, it wanteth eternity, it wanteth recurrence, it wanteth everything eternally-like-itself.