I want to begin with a bold conjecture: perhaps Irigaray’s work on sexual difference might find unexpected confirmation from Darwin’s account of sexual selection. Ironically, it may turn out that Irigaray finds the greatest philosophical confirmation of her claims regarding sexual difference from Darwin’s understanding of the power and force of sexual selection. And, with equal irony, Darwin’s work may be interpreted not only as a systematic account of the forces that compose and transform natural existence but also as the first theoretical framework that makes the amorphous forces of sexual attraction and sexual differentiation productive of the richness and complexity of life. If Irigaray sees sexual difference as the motor of cultural life, Darwin sees it as the motor of natural existence. Can Irigaray’s concept find resonance in biological theory? Can biology provide feminist thought with the conceptual resources by which to understand sexual difference?