There is an idea, a beautiful idea, a wonderful idea, that, for some reason, I equate primarily with Death Metal. The idea of letting one's inner emotions out, even if just for a moment, and allowing yourself to Unleash the Beast Within.
That last part of the line there is probably why I equate the concept with Death Metal. Can't you just hear the line "Unleash the beast within" roared throatily into a microphone by some nordic guy who looks like the scary ghost girl from "The Ring".
Now it is usually pretty easy to let your positive emotions out. If you see a giant teddy bear…
you can probably hug it. If you see a cuddly puppy...
you can probably go "awwwwwwwwww" and nobody will really look at you funny… except for maybe the Death Metal guy.
The hard part comes from letting your negative emotions out. I don't mean getting home from work one day, walking into the bathroom, closing the door and just screaming
"FUCKING BALLS IN A BLENDER!!!!!"
because anyone can do that. While that is freeing the beast within, it's doing it as an afterthought, it's what happens when emotions are bottled up.