Nietzsche expanded on this thought to form his theory , which he put forth in " The Gay Science " and developed in " Thus Spoke Zarathustra " .
Head entity: thus spoke zarathustra Q199774 24 25 26
Tail entity: the gay science Q1061693 16 17 18
Relation (head \u2192 tail): P156
Inverse relation (tail \u2192 head): P155