  Since the corpuscular hypothesis holds impulse to be the primary if not the sole means by which bodies causally interact, then any phenomenon that the corpuscular hypothesis purports to explain by impulse is obscure if impulse itself is obscure. All of the hypothesis’ reductions of observable primary qualities, of secondary qualities, and of tertiary qualities, would inherit impulse’s obscurity; thus Locke appears to be suggesting here that the corpuscular hypothesis cannot fulfill its promise of explaining and reducing those properties and powers.