Aristotle, Politics

¹In all the arts and the sciences that are not merely sectional but that in relation to some one class of subject are complete, it is the function of a single art or science to study what is suited to each class,² for instance what sort of gymnastic exercise is beneficial for what sort of bodily frame, and what is the best sort （for the best must naturally suit the person of the finest natural endowment and equipment）, and also what one exercise taken by all is the best for the largest number （for this is also a question for gymnastic science）, and in addition, in case someone desires a habit of body and a knowledge of athletic exercises that are not the ones adapted to him, it is clearly just as much the task of the trainer and gymnastic master to produce this capacity³ also; [20] and we notice this also happening similarly in regard to medicine, and shipbuilding, and the making of clothes, and every other craft. Hence it is clear that in the case of the constitution as well it is the business of the same science to study which is the best constitution and what character it must have to be the most ideal if no external circumstance stands in the way, and what constitution is adapted to what people （since for many it is doubtless impossible to attain the best one, so that the good lawgiver and the true statesman must be acquainted with both the form of constitution that is the highest absolutely and that which is best under assumed conditions）, and also thirdly the form of constitution based on a certain supposition （for he must be also capable of considering both how some given constitution could be brought into existence originally and also in what way having been brought into existence it could be preserved for the longest time: I mean for example if it has befallen some state not only not to possess the best constitution and to be unprovided even with the things necessary for it, but also not to have the constitution that is practicable under the circumstances but an inferior one）; and beside all these matters he must ascertain the form of constitution most suited to all states, since most of those who make pronouncements about the constitution, even if the rest of what they say is good, entirely miss the points of practical utility. For it is proper to consider⁴ not only what is the best constitution but also what is the one possible of achievement, and likewise also what is the one that is easier and more generally shared by all states. But as it is, some students inquire which is the highest form of all even though requiring much material equipment,⁵ while those who rather state some general form sweep aside the constitutions actually existing and praise that of Sparta or some other;