I traced it out evolutionarily to the olfactory system, which makes absolutely wonderful sense (scents) — not that other senses are necessarily patterned exactly after the olfactory system because they’re not – but they’re later-comers and “hooked in”.
But then when I wanted to back from the volotile chemicals (or volitile organic compounds) back through the olfactory system to the ‘gist’ which was my goal – yikes, what a headache.