 That is not to say that Newton had no understanding of how such effects would be explained in his mechanics. For instance, in Corollaries V and VI to the Definitions of the Principles he states in general terms the conditions under which different states of motion are not – and so by implication are – discernible according to his laws of mechanics. Nor is it to say that Newton’s contemporaries weren’t seriously concerned with explaining inertial effects. Leibniz, for instance, analyzed a rotating body (in the Specimen). In short, parts of a rotating system collide with the surrounding matter and are continuously deflected, into a series of linear motions that form a curved path. (Though the system as Leibniz envisions it – comprised of a plenum of elastic particles of matter – is far too complex for him to offer any quantitative model based on this qualitative picture. So he had no serious alternative explanation of inertial effects.)