True beliefs require directed input
Bayes’ Theorem (whether implicitly or explicitly) is what is used to direct “belief energy” towards true beliefs. This is like how a machine needs energy input to continue running.
It may even be more than a metaphor, if we take the idea that Entropy is the tendency of a system to progress towards technical simplicity, and Bayes’ Theorem may be a tool for helping us see the flow of Entropy.
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“If you saw a machine continually spinning a wheel, apparently without being plugged into a wall outlet or any other source of power, then you would look for a hidden battery, or a nearby broadcast power source—something to explain the work being done, without violating the laws of physics. So if a mind is arriving at true beliefs, and we assume that the Second Law of Thermodynamics has not been violated, that mind must be doing something at least vaguely Bayesian—at least one process with a sort-of Bayesian structure somewhere—or it couldn’t possibly work.” (Eliezer Yudkowsky, Rationality)