In this paper I clarify what Newton could have meant when he insisted that gravity is a real force. I interpret Newton’s speculative treatment of gravity as a relational, accidental quality of matter that arises through what Newton calls “the shared action” of two bodies. I argue that when Newton drafted the first edition of the Principia in the mid 1680s, he thought that (at least a part of) the cause of gravity is the disposition inherent in any individual body, but that the force of gravity is the actualization of that disposition; a necessary condition for the actualization of the disposition is the actual obtaining of a relation between two bodies having the disposition. The cause of gravity is not essential to matter because God could have created matter without that disposition. Nevertheless, at least a part of the cause of gravity inheres in individual bodies and were there one body in the universe it would inhere in that body. On the other hand, the force of gravity is neither essential to matter nor inherent in matter, because (to repeat) it is the actualization of a shared disposition. A lone part-less particle would, thus, not generate a gravity field.