It may be supposed, that in the evenings after the agricultural labours of the morning, and after his friends had left him, he noted down the precepts suggested by the observations and experience of the day. That he wrote such maxims for his own use, or the instruction of others, is unquestionable; but the treatise _De Re Rustica_, which now bears his name, appears to have been much mutilated, since Pliny and other writers allude to subjects as treated of by Cato, and to opinions as delivered by him in this book, which are nowhere to be found in any part of the work now extant.
In its present state, it is merely the loose unconnected journal of a plain farmer, expressed with rude, sometimes with almost oracular brevity; and it wants all those elegant topics of embellishment and illustration which the subject might have so naturally suggested. It solely consists of the dryest rules of agriculture, and some receipts for making various kinds of cakes and wines. Servius says, it is addressed to the author's son; but there is no such address now extant. It begins rather abruptly, and in a manner extremely characteristic of the simple manners of the author: "It would be advantageous to seek profit from commerce, if that were not hazardous; or by usury, if that were honest: but our ancestors ordained, that the thief should forfeit double the sum he had stolen, and the usurer quadruple what he had taken, whence it may be concluded, that they thought the usurer the worst of the two. When they wished highly to praise a good man, they called him a good farmer. A merchant is zealous in pushing his fortune, but his trade is perilous and liable to reverses. But farmers make the bravest men, and the stoutest soldiers. Their gain is the most honest, the most stable, and least exposed to envy. Those who exercise the art of agriculture, are of all others least addicted to evil thoughts."
Our author then proceeds to his rules, many of which are sufficiently obvious. Thus, he advises, that when one is about to purchase a farm, he should examine if the climate, soil, and exposure be good: he should see that it can be easily supplied with plenty of water,--that it lies in the neighbourhood of a town,--and near a navigable river, or the sea. The directions for ascertaining the quality of the land are not quite so clear or self-evident. He recommends the choice of a farm where there are few implements of labour, as this shews the soil to be easily cultivated; and where there are, on the other hand, a number of casks and vessels, which testify an abundant produce. With regard to the best way of laying out a farm when it is purchased, supposing it to be one of a hundred acres, the most profitable thing is a vineyard; next, a garden, that can be watered; then a willow grove; 4th, an olive plantation; 5th, meadow-ground; 6th, corn fields; and, lastly, forest trees and brushwood. Varro cites this passage, but he gives the preference to meadows: These required little expense; and, by his time, the culture of vines had so much increased in Italy, and such a quantity of foreign wine was imported, that vineyards had become less valuable than in the days of the Censor. Columella, however, agrees with Cato: He successively compares the profits accruing from meadows, pasture, trees, and corn, with those of vineyards; and, on an estimate, prefers the last.