"Essences don't have to be "undefinable". That is defeatist. "

The very term "undefinable essence" refers to something that is unknowable... at present. How we approach this unknowability is part of what I'm discussing with Joe; he and I don't approach it the same way. Science is very familiar with the unknowable, and strives to make it known, however there is still so much we don't know and don't have a clue about or even a frame of reference to discuss what might no know or suspect the existence of.

So what you call "defeatist", I call pragmatic. I am trying to find common ground in which to explore the differences in two philosophical systems. I can't speak for Joe about how he address the "undefinable essence", but as a scientist (and artist I would argue) my work is a tiny,tiny, tiny weeny part of the collective effort of all scientists in chipping away at the unknowable via the scientific method, supported the philosophy that underpins that method. This is how we, as scientists, attempt to confront the feeling of the existence of an "undefinable essence", and to try to reveal it's true nature.

Just to note, Joe used the phrase "unifying essence" which is a different matter entirely, and an interesting one for discussion. After all, unifying theories are the stuff of science...