Fire represents passion, enthusiasm, hunger, need, rushing in.
Plasma is the state matter gets to when it gets hot enough to rip things apart. When it interacts with other states of matter spectacular effects can be produced.
AIRAir represents intellect, thought, reasoning.
In a gas the different parts of things rarely really touch, they are only loosely associated. Gas expands to fill the space it is in.
ATERWater represents emotion, creativity.
Water cannot be compressed, squashed away someplace. The more you try to squash it the more it gets everywhere. It always finds its own level. It is very powerful, just watch the ocean in a storm, or find out about erosion. You can lock it in a box but it will soak through or rust through eventually.
EARTHEarth represents the physical, that which can be seen and touched, nourishment, money.
Solids often seem to stay unaltered by the other things but there are always subtle changes going on. They are often slow to change, but fire can change them utterly in minutes.
SOULSoul is that which we are all made of, that which continues between lifetimes.
When things get cold enough, within a 0.000001 degrees of absolute zero, a fundamental change appears to come over them. atoms forget their seperate identities and become part of one greater entity. The laws that govern this state appear different from the everyday laws, since quantum mechanical effects are clear that are obscured in hotter states.
These thoughts are still very very rough.