90. Heavy, melancholy men turn lighter, and come temporarily to their surface, precisely by that which makes others heavy—by hatred and love.
Remember, he seems to use love to mean a creative spirit and energy, not relationships. He repeated stresses that the ideal man should be a loner. Therefore, here he seems to be talking about how the effort to be creative can seem heavy to normal people, but a manic / depressive cylcing person needs that charged burst of creative energy to feel lighter.
Addendum: His failed relationship with Lou Salomé might be read into several of the aphorisms. He might have been talking about love after all.
