The sand does not control its environment, having been ground early on in existence. Moving and blowing in the breeze, it no longer retains its original structure.  It can be put it in a jar and taken anywhere, molding to the shape of its container.  Without external structure or force, it has no shape, no mobility.  It is forever at the whims of others with the recollection that it was not always this way.  Knowing that it had its own structure is to be aware that it is capable of existing independently, yet unable to and slowly forgetting how to find its way back to solidity.