Xenophon's Economics is a controversial writing. Some readers consider it a text devoid of any rationality in the economic field while others detect in it a precapitalist rationality based on the search for the maximization of utility. This article hypothesizes a third way: the object of Xenophon's Economics is to reflect on how economic practices engage, on the one hand, an instrumental rationality involving procedures of choice comparing risks and benefits with a view to maximizing gain, and, on the other hand, a practical rationality probing the value of means and ends, and limiting the possibility of the autonomy of instrumental reason, i.e., its tendency to become irrational. I examine in detail how these two uses of reason are expressed, exercised, and articulated in the Economics, and I show that Xenophon formulates a decisive question of economic epistemology, with very tangible practical and material implications.