The metaphor of physical law - a range of orderly behavior within certain authoritative constraints - has not escaped the historians of ideas. That scheme, in all its forms, east and west, gained its earliest strength from astronomy itself. The search for measured order in heaven is old and widespread; two instances from ancient China and pre-Columbian Mexico will make the point.

For our modern science, two universals rule: that of particulate matter - from neutrons to C2 H5 OH - and the only unsaturable force, long-range gravitation. The phenomena of astronomical scale are mainly examples of kinetic motion resisting for a time that untiring attraction, under the virial theorem. Matter is everywhere familiar, apart from the deep and puzzling question of what seems to be the large-scale failure of matter-antimatter symmetry.