  This section examines the phenomena that Locke seems to consider too obscure for the corpuscular hypothesis to illuminate. These are the three phenomena mentioned in the above-quoted passage, the production of sensation, the communication of motion,  cohesion,[17] and a fourth, gravity, which Locke discusses directly only outside the Essay. A subsequent section reviews some of the main positions that have been taken in the debate about the status of the corpuscular hypothesis for Locke, and that same section considers various interpretations of superaddition, since any interpretation of that concept is logically tied to one’s view about Locke’s stance toward the corpuscular hypothesis.