Thus Spoke Zarathustra

"Man is for woman a means: the purpose is always the child. But what is woman for man?

The real man wants two different things: danger and play. Therefore he wants woman, as the most dangerous plaything."

-- Excerpt from "Thus Spoke Zarathustra" by Friedrich Nietzsche,
part I, chapter XVIII, "Old And Young Women"

And perhaps the motives behind irresistible attraction, addiction and passion for motorcycles are also revealed through those words.