In a 2D world, two travelers at the equator of a sphere at different points on the equator travel North starting parallel to each other. As they move up the latitude, they gradually approach each other as they maintain their longitude geodesic. They interpret the closing linear distance as acceleration towards each other and a "force of attraction." In reality, it is the curved 2D surface that draws them together. The question is: what makes them move north in the first place. If they sat still on the equator there would be no relative motion towards each other and no "gravity." My take is that with referfence to this 2D world, the northward movement would be due to the time coordinate in the third dimension not seen in the 2D world and worldline expansion, which would occr even if both bodies were totaly at rest on the surface with respect to each other and the movement would not be averted and the "gravity" would still appear. I assume, analogously in our 3D world, the unseen 4th dimension, time, marches on and there is always a worldline created in spacetime which is ever getting longer and this line, if subject to an uneven or curved spacetime would likewise come out as gravity as the world lines would not be "straight."