Why do we hesitate, then, to inquire as to his whole nature, what has been done? For as it is agreed by all, that the whole duty and office of wisdom is to be occupied aboutthe cultivation of man, some (that you may not think that I am arguing against none but the Stoics) bring forward opinions in which they place the chief good among things of a kind which are wholly out of our own power, just as if they were speaking of one of the brute beasts; others, on the contrary, as if man had no body at all, so entirely exclude everything from their consideration except the mind, (and this, too, while the mind itself, in their philosophy, is not some unintelligible kind of vacuum, but something which exists in some particular species of body,) that even that is not content with virtue alone, but requires freedom from pain. So that both these classes do the same thing, as if they neglected the left side of a man, and took care only of the right; or as if they (as Herillus did) attended only to the knowledge of the mind itself, and passed over all action. For it is but a crippled system which all those men set up who pass over many things, and select some one in particular to adhere to. But that is a perfect and full system which those adopt who, while inquiring about the chief good of man, pass over in their inquiry no part either of his mind or body, so as to leave it unprotected. But your school, O Cato, because virtue holds, as we all admit, the highest and most excellent place in man, and because we think those who are wise men, perfect and admirable men, seeks entirely to dazzle the eyes of our minds with the splendour of virtue. For in every living creature there is some one principal and most excellent thing, as, for instance, in horses and dogs; but those must be free from pain and in good health. Therefore, you do not seem to me to pay sufficient attention to what the general path and progress of nature is. For it does not pursue the same course in man that it does in corn, (which, when it has advanced it from the blade to the ear, it leaves and considers the stubble as nothing,) and leave him as soon as it has conducted him to a state of reason. For it is always taking something additional, without ever abandoning what it has previously given. Therefore, it has added reason to the senses; and when it has perfected his reason, it still does not abandon the senses.
As if the culture of the vine, the object of which is to cause the vine, with all its parts, to be in the best possible condition, (however that is what we understand it to be, forone may, as you often do yourselves, suppose anything for the purpose of illustration,) if, then, that culture of the vine be in the vine itself, it would, I presume, desire everything else which concerns the cultivation of the vine, to be as it has been before. But it would prefer itself to every separate part of the vine, and it would feel sure that nothing in the vine was better than itself. In like manner sense, when it has been added to nature, protects it indeed, but it also protects itself. But when reason is also added, then it is placed in a position of such predominant power, that all those first principles of nature are put under its guardianship. Therefore it does not abandon the care of those things over which it is so set, that its duty is to regulate the entire life: so that we cannot sufficiently marvel at their inconsistency. For they assert that the natural appetite, which they call ὁρμὴ, and also duty, and even virtue herself, are all protectors of those things which are according to nature. But when they wish to arrive at the chief good, they overleap everything, and leave us two tasks instead of one—namely, to choose some things and desire others, instead of including both under one head.