principles and essences, mainly
because their mode of investigation is a logical one. The older
philosophers, on the other hand, considered particular things to be
essences; _e.g.,_ fire and earth, not body in general.

There are three essences. Two of these are sensible, one being eternal
and the other transient. The latter is obvious to all, in the form of
plants and animals; with regard to the former, there is room for
discussion, as to whether its elements are one or many. The third,
differing from the other two, is immutable and is maintained by certain
persons to be separable. Some make two divisions of it, whereas others
class together, as of one nature, ideas and mathematical entities; and
others again admit only the latter. The first two essences belong to
physical science, for they are subject to change; the last belongs to
another science, if there is no principle common to all.

ON COMMUNITY OF STUDIES

From 'The Politics,' Book 8

No one, therefore, can doubt that the legislator ought principally to
attend to the education of youth. For in cities where this is neglected,
the politics are injured. For every State ought to be governed according
to its nature; since the appropriate manners of each polity usually
preserve the polity, and establish it from the beginning. Thus,
appropriate democratic manners preserve and establish a democracy, and
oligarchic an oligarchy. Always, however, the best manners are the cause
of the best polity. Further still, in all professions and arts, there
are some things which ought previously to be learnt, and to which it is
requisite to be previously accustomed, in order to the performance of
their several works,; so that it is evident that it is also necessary in
the practice of virtue.

Since, however, there is one purpose to every city, it is evident that
the education must necessarily be one and the same in all cities; and
that the attention paid to this should be common. At the same time,
also, no one ought to think that any person takes care of the education
of his children separately, and privately teaches them that particular
discipline which appears to him to be proper. But it is necessary that
the studies of the public should be common. At the same time, also, no
one ought to think that any citizen belongs to him in particular, but
that all the citizens belong to the city; for each individual is a part
of the city. The care and attention, however, which are paid