Cogito Ergo Sum

I am a brain -
   sarcastic intellectualising of the rampant id,
the deadly satire -
   those moving buttocks' machinations - of my own
indecency.

I'm a membrane,
   thin sheet of low-grade textbook education
kept braced and tuned
   by my anxiety - it is a good thing I'm
not free.

I'm in a cage -
   cast-iron bearcage round a roaring beast,
an inbred safety valve,
   a razorblade between my brother's wife
and me.

I am a brain -
   I'm no emotions but frigid calculation,
expectation -
   with clinical reason my only excuse
to be.