While cleaning out my files--digital files, of course--I found an old presentation on the Euler Characteristic that I gave in Differential Geometry. This element is called an invariant, and it happens to be the most fundamental link between topology, geometry, and analysis.
Indeed, in mathematics it seems as though the invariants are the most beautiful and elegant constructs. Invariants are unchanging by definition, and descriptive by nature, but most importantly they are the twisting trunks of magnificent trees from which all of mathematics can blossom forth. (Poetry aside, it's quite true how all fields of mathematics always tend to boil down to the same few invariants. Similarly, these invariants, although often hidden, always reappear in calculations or theoretical deconstructions.)
Are there invariants for humans?
Perhaps intelligence. My intelligence characteristic might be different than yours, everyone has a constant one, and it separates each of us into classes (figuratively and otherwise).
Perhaps beauty. This innate quality uniquely defines each and every human, yet it also stratifies and lends itself to further analysis.
Perhaps personality. While some are sharp with their tongues, others are sharp with their wits. Some are quick to assault, others are quick to resolve. However each and every person has a personality which defines him, and so it too may be an invariant.
What makes us human is the lack of invariance. While mathematics has order and structure, it is the organic nature of humanity which precludes any sort of regularity and begs for variance.
If mathematics is the massive, gnarled oak, humanity is the field of wildflowers.
And then does it follow that there is no invariant in the world of Web 2.0? Currently, I'm on a sort of crusade to find one. Any one have any ideas?