Sorry but i have a question regarding Laplace Equation, say if a potential function P represents the inverse square propotional field, then how am i going to visualize taking twice partial derivative of P is equal to zero? Because since grad of P is pointing inward (which looks to me is a sink at the centre of the gravitation point (x0,y0,z0)), so how am i going to say that divergence of grad(P) is equal to zero? (since the grad(P) the vector is pointing inward), I mean i have seen some proofs of it which leads to the final conclusion of Laplace Equation, but how am i going to visualize it in a way that it makes sense that grad(P) is pointing no-where? (since divergence of grad(P) should be zero, which means neither sink or source, but isn't gravitation a sink? ).