snowflake

two molecules of water can't form ice
at best, they share a single hydrogen
no less than five could possibly suffice
to sketch the unit right tetrahedron
thereafter, each incomer's free to dock
if its kinetic energy's alright
forsaking role as gas for role as rock
to claim a free coordination site
six vertices in six directions grow
each independently hews to the norm
as building blocks march outwards, row by row
defining a new snowflake's starry form
reductionism picks a thing apart
to grasp it by the method of Descartes