Complex sentence: Freud claims this is a manifestation of a "passive homosexual" childhood fantasy that Leonardo wrote about in the Codex Atlanticus, in which he recounts being attacked as an infant in his crib by the tail of a vulture.
Split into simpler sentences: Freud claims this is a manifestation of a "passive homosexual" childhood fantasy Leonardo wrote about in the Codex Atlanticus. Using Freud's translation, Leonardo recounts being attacked as an infant in his crib by the tail of a vulture.