evidence: Socrates is committed to the theme that ruling is a kind of craft or art (technē). As such, it requires knowledge. Just as a doctor brings about a desired result for his patient—health, for instance—so the ruler should bring about some desired result in his subject (Republic 341c-d, 342c). Medicine, insofar as it has the best interest of its patient in mind, never seeks to benefit the practitioner. Similarly, the ruler’s job is to act not for his own benefit but for the benefit of the citizens of the political community. This is not to say that there might not be some contingent benefit that accrues to the practitioner; the doctor, for instance, might earn a fine salary. But this benefit is not intrinsic to the expertise of medicine as such. One could easily conceive of a doctor that makes very little money. One cannot, however, conceive of a doctor that does not act on behalf of his patient. Analogously, ruling is always for the sake of the ruled citizen, and justice, contra the famous claim from Thrasymachus, is not whatever is in the interest of the ruling power (Republic 338c-339a).