If gravity is understood as the relative contraction of space intervals, and the relative expansion of time intervals, by a massive body, then gravity is neither the curvature of space nor the curvature of time. What is curved is the geodesic, the minimum distance between two points in space, which is the trajectory a body will take unless acted upon some other force. This is because the minimum distance, say for a moon moving relative to a planet, is always in the direction of the planet, since this is the direction in which space intervals are contracted.