Aristotle, Nicomachean Ethics
H. Rackham, Ed.

This indeed is the moving cause of productive activity¹ also, since he who makes some thing always has some further end in view: the act of making is not an end in itself, it is only a means, and belongs to something else. Whereas a thing done is an end in itself: since doing well （welfare²） is the End, and it is at this that desire aims.

Hence Choice may be called either thought related to desire or desire related to thought; and man, as an originator of action, is a union of desire and intellect.2. [6]

（Choice is not concerned with what has happened already: for example, no one chooses to have sacked Troy; for neither does one deliberate about what has happened in the past, but about what still lies in the future and may happen or not; what has happened cannot be made not to have happened. Hence Agathon is right in saying “ This only is denied even to God,
The power to make what has been done undone.）

” The attainment of truth is then the function of both the intellectual parts of the soul. Therefore their respective virtues are those dispositions which will best qualify them to attain truth.3.

Let us then discuss these virtues afresh, going more deeply into the matter.

Let it be assumed that there are five qualities through which the mind achieves truth in affirmation or denial, namely Art or technical skill,³ Scientific Knowledge, Prudence, Wisdom, and Intelligence. Conception and Opinion are capable of error. 3. [2]

The nature of Scientific Knowledge （employing the term in its exact sense and disregarding its analogous uses） may be made clear as follows. We all conceive that a thing which we know scientifically cannot vary; when a thing that can vary is beyond the range of our observation, we do not know whether it exists or not. An object of Scientific Knowledge, therefore, exists of necessity. It is therefore eternal, for everything existing of absolute necessity is eternal; and what is eternal does not come into existence or perish. 3. [3] Again, it is held that all Scientific Knowledge can be communicated by teaching, and that what is scientifically known must be learnt. But all teaching starts from facts previously known, as we state in the Analytics,⁴ since it proceeds either by way of induction, or else by way of deduction. Now induction supplies a first principle or universal, deduction works from universals; therefore there are first principles from which deduction starts, which cannot be proved by deduction; therefore they are reached by induction. 3. [4] Scientific Knowledge, therefore, is the quality whereby we demonstrate,⁵ with the further qualifications included in our definition of it in the Analytics,⁶ namely, that a man knows a thing scientifically when he possesses a conviction arrived at in a certain way, and when the first principles on which that conviction rests are known to him with certainty—for unless he is more certain of his first principles than of the conclusion drawn from them he will only possess the knowledge in question accidentally.⁷ Let this stand as our definition of Scientific Knowledge.