The general attitude of Plato toward economic production may be inferred from his insistence upon the thorough application of the division of labor for the perfection of industry.[120] He evidently recognized it as the necessary basis of all higher life. We have seen above, also that one of his chief objections to excessive wealth or poverty was the fact that they caused inefficiency in production. _Agriculture._—Of the three factors that enter into production—land, labor, and capital—the most important in the mind of the Greek thinkers was land. The relative prominence of agriculture was partly the cause of this, but in the case of the philosophers, their ethical passion, their idea of the necessity of leisure for personal development, and their conservative attitude toward industry and commerce were the chief motives that impelled them to urge their contemporaries back to the simple life of the farm.[121] The aristocratic feeling, still strong in European countries, that landed property is the most respectable, probably also had some influence, though land was not so distinctively in the hands of the upper classes in Attica. Though the praise of agriculture was a characteristic feature of Greek literature in all periods, it was not at first a conscious economic theory.[122] Later, toward the end of the fifth century, it became a definite ethico-economic doctrine of the philosophers, as a criticism of their times, and as an appeal to what was deemed to be the more healthful life of the earlier days. Plato does not devote so much attention to this theme as do Xenophon and Aristotle. His standpoint, however, is practically the same, though his tendency toward the physiocratic error is not so marked. In his second state, he orders that agriculture shall be the only means of money-making,[123] and he even strikes the modern note of conservation, in his directions for the care of land, waters, springs, and forests.[124] On this point, he and the other Greek thinkers accord well with the economy of the past decade with its urgent preachment, “Back to the land,” though the modern watchword has, of course, a more economic emphasis. _Capital._—Though the function of capital, aside from natural resources, was a familiar fact in the Athenian life of the fifth and fourth centuries B.C.,[125] there is scarcely any consideration of it by the theorists before Aristotle. Plato has no definition of capital, nor indeed scarcely any recognition of the fact of its existence.[126] His emphasis on the virtue of economy, however, and his criticism of those who spend the “stored wealth,” imply the idea that wealth should be used not merely for enjoyment, but also for productive purposes.[127] His strictures upon interest show that he has but slight appreciation of the productive function of money-capital.[128]