that happiness is a
thing honored and perfect.
This seems to be borne out by
the fact that it is a first principle or starting-point, since all other things that all
men do are done for its sake; and that which is the first principle and cause of things
good we agree to be something honorable and divine.13.
But inasmuch as happiness is a certain activity of soul in conformity with perfect
virtue, it is necessary to examine the nature of virtue. For this will probably assist us
in our investigation of the nature of happiness.
the true statesman seems to be one who has made a special study of goodness, since his aim
is to make the citizens good and law-abiding men—
witness the lawgivers of Crete
, and the other great legislators of history;
but if the study of virtue falls within the province of
Political Science, it is clear that in investigating virtue we shall be keeping to the
plan which we laid down at the outset.
Now the goodness that we have to consider is clearly human virtue, since the good or
happiness which we set out to seek is human good and human happiness.
But human virtue means in our view excellence of soul, not excellence of
body; also our definition of happiness is an activity of the soul.
Now if this is so, clearly it behoves the statesman to have some
acquaintance with psychology, just as the physician who is to heal the eye or the other parts of the body1
must know their anatomy. Indeed a foundation of science is even more
requisite for the statesman, inasmuch as politics is a higher and more honorable art than
medicine; but physicians of the better class devote much attention to the study of the
The student of politics2
therefore as well as the psychologist must study the nature of the soul,
though he will do so as an aid to politics, and only so far as is requisite for the
objects of enquiry that he has in view: to pursue the subject in further detail would
doubtless be more laborious than is necessary for his purpose.
Now on the subject of psychology some of the teaching current in extraneous
is satisfactory, and
may be adopted here: namely that the soul consists of two parts, one irrational and the
other capable of reason.4
（Whether these two parts are really distinct in
the sense that the parts of the body or of any other divisible whole are distinct, or
whether though distinguishable in thought as two they are inseparable in reality, like the
convex and concave sides of a curve, is a question of no importance for the matter in
Of the irrational part of the soul again
one division appears to be common to all living things, and of a vegetative nature: I
refer to the part that causes nutrition and growth; for we must assume that a vital
faculty of this nature exists in all things that assimilate nourishment,