  The fact that collisions between actual bodies are never perfectly  elastic represents a prima facie objection to the  conservation of vis viva. Although the law looks tolerably  accurate if we consider the collision of, say, two billiard balls, or two steel spheres, it seems woefully off if we consider, say, the  collision of two lumps of clay, or two scoops of ice cream. Indeed,  in non-elastic collisions it appears that much – even all  – of the active force of the colliding bodies as measured by  mv2 may be lost. In addressing this  fairly obvious worry, Leibniz returns to the idea that any body  – no matter how small – must be composed of infinitely  many smaller bodies. He then argues that the apparent loss of vis viva in cases of inelastic collision is to be attributed to the  fact that living force has been transferred to the smaller parts of  the gross bodies in a way that does not contribute fully to the  motion of the whole. It is thus lost in the sense that it does not  contribute to the motion of the larger bodies, but it is nonetheless  conserved in the deeper sense that it is still present in the motion  of the smaller bodies from which the larger bodies are constituted.  Leibniz therefore insists, “when the parts of the bodies absorb the force of the impact, as a whole, as when two pieces of rich earth or clay come into collision … when, I say, some force is  absorbed by the parts, it is as good as lost … But this loss  … does not detract from the inviolable truth of the law of the conservation of the same force in the world. For that which is  absorbed by the minute parts is not absolutely lost for the universe, although it is lost for the total force of the concurrent  bodies” (GM VI.230/Langley 670).