Aristotle, Nicomachean Ethics
H. Rackham, Ed.

the Virtues of the Character and the Virtues of the Intellect. The former, the Moral Virtues, we have already discussed. Our account of the latter must be prefaced by some remarks about psychology.1. [5]

It has been said before¹ that the soul has two parts, one rational and the other irrational. Let us now similarly divide the rational part, and let it be assumed that there are two rational faculties, one whereby we contemplate those things whose first principles are invariable, and one whereby we contemplate those things which admit of variation: since, on the assumption that knowledge is based on a likeness or affinity of some sort between subject and object, the parts of the soul adapted to the cognition of objects that are of different kinds must themselves differ in kind. 1. [6] These two rational faculties may be designated the Scientific Faculty and the Calculative Faculty respectively; since calculation is the same as deliberation, and deliberation is never exercised about things that are invariable, so that the Calculative Faculty is a separate part of the rational half of the soul.1. [7]

We have therefore to ascertain what disposition of each of these faculties is the best, for that will be the special virtue of each.

But the virtue of a faculty is related to the special function which that faculty performs. 2. Now there are three elements in the soul which control action and the attainment of truth: namely, Sensation, Intellect,² and Desire.2. [2]

Of these, Sensation never originates action, as is shown by the fact that animals have sensation but are not capable of action.³

⁴Pursuit and avoidance in the sphere of Desire correspond to affirmation and denial in the sphere of the Intellect. Hence inasmuch as moral virtue is a disposition of the mind in regard to choice,⁵ and choice is deliberate desire,⁶ it follows that, if the choice is to be good, both the principle must be true and the desire right, and that desire must pursue the same things as principle affirms. 2. [3] We are here speaking of practical thinking, and of the attainment of truth in regard to action; with speculative thought, which is not concerned with action or production, right and wrong functioning consist in the attainment of truth and falsehood respectively. The attainment of truth is indeed the function of every part of the intellect, but that of the practical intelligence is the attainment of truth corresponding to right desire.⁷ 2. [4]

Now the cause of action （the efficient, not the final cause） is choice,⁸ and the cause of choice is desire and reasoning directed to some end. Hence choice necessarily involves both intellect or thought and a certain disposition of character [⁹ for doing well and the reverse in the sphere of action necessarily involve thought and character].2. [5]

Thought by itself however moves nothing, but only thought directed to an end, and dealing with action.