The most distinctive point about the doctrine of the first book is its separation of οἰκονομική from πολιτική as a special science.[879] The author agrees with Aristotle, however, that it is the function of economics both to acquire and to use, though without his specific limitations upon acquisition.[880] He distinguishes four forms of economy—acquiring, guarding, using, and arranging in proper order.[881] Elsewhere, he makes a different classification on another basis—imperial, provincial, public, and private.[882] These are each further subdivided, the first including finance, export and import commerce, and expenditures.[883] Agriculture is especially eulogized by the author, in the spirit of Xenophon and Aristotle. It is the primary means of natural acquisition, the others being mining and allied arts whose source of wealth is the land.[884] It is the most just acquisition, since it is not gained from men, either by trade, hired labor, or war,[885] and it contributes most to manly strength.[886] Retail trade and the banausic arts, on the other hand, are both contrary to nature,[887] since they render the body weak and inefficient (ἀχρεῖα).[888] The work agrees with Aristotle, against Plato, in his doctrine that men and women are essentially different in nature, and hence that their work should be distinct.[889] No attempt is made to justify slavery, though Aristotle is followed in his advice to grant emancipation, as a special reward for faithfulness.[890] The author of Book ii seems to have taken for granted the Cynic theory that money need have no intrinsic value, at least for local purposes. Coinage of iron,[891] tin,[892] bronze,[893] the arbitrary stamping of drachmas with a double value,[894] are all offered apparently as a proper means of escape from financial difficulty. Like Aristotle, he accepts monopoly as a shrewd and legitimate principle of finance.[895] Elsewhere, however, in striking contrast to such uneconomic suggestions, the author states the important economic principle that expenditures should not exceed income.[896] In accord with Greek usage, he is familiar with a tax on exports for revenue and as a means of guarding against depletion of supply.[897] CYRENAICS The Cyrenaics were the forerunners of the Epicureans in their more liberal attitude toward wealth. Aristippus,[898] the founder of the school, was a man of the world, who believed in enjoying life as it came.[899] He held that pleasure was always a good, and that all else was of value only as a means of realizing this end.[900] If consistent, therefore, he must have valued highly moderate wealth. His principle that one should aim to realize the highest degree of pleasure with the least economic expenditure is somewhat analogous to the modern economic doctrine of the smallest means.[901] Bion of Borysthenes became a Cyrenaic in his later life, but his satires are almost entirely lost.[902]