Lust is purely physical...a very primal feeling/emotion/reaction...to physical stimuli. That's how I think of "lust."
That "moment of passion" where...as soon as you were finished, you can't remember how it all began.
I see love as the most complicated human emotion...it can be the bringer of great joy and in the next moment, it'll cut you so fast and deeply that you're stunned and hurt beyond all that you know.
