[How about this metaphor?

The person’s psyche is like a steam engine.

Perhaps, the normal contexts of think and law act like regulators. Conscience and dispositions act like fuel.

Sigmund Freud, one of the founders of psychoanalysis, started with a picture of the unconscious as a steam engine powering a locomotive.

Freud wrote between 1890 and 1950 AD (7690-7750 U0′).]