question: Having studied only Newtonian physics, and a very limited amount of 
it at that, I find it impossible to believe in the existence of 
solids, although experience tells me that there is probably something
in the hypothesis that there really is solid matter.  Presumably
quantum mechanics goes some way toward explaining this strange
phenomenon.  What I want to know is similar.  Does physics currently
have any good explanation for the fact that small molecules
invariably form crystals (in the solid phase) and that the forms of
these crystals are very specific, although there might be more than
one type possible for any given molecule depending upon temperature
and pressure.  If there is such an explanation, can it predict the
form of the crystal on the basis of anything known about the molecule?