is as necessarily true, as that a
whole is greater than its part. (Cf. III. iv.)

Again, as virtue is nothing else but action in accordance
with the laws of one's own nature (IV. Def. viii.), and as no one
endeavours to preserve his own being, except in accordance with
the laws of his own nature, it follows, first, that the
foundation of virtue is the endeavour to preserve one's own
being, and that happiness consists in man's power of preserving
his own being; secondly, that virtue is to be desired for its
own sake, and that there is nothing more excellent or more useful
to us, for the sake of which we should desire it; thirdly and
lastly, that suicides are weak--minded, and are overcome by
external causes repugnant to their nature. Further, it follows
from Postulate iv., Part II., that we can never arrive at doing
without all external things for the preservation of our being or
living, so as to have no relations with things which are outside
ourselves. Again, if we consider our mind, we see that our
intellect would be more imperfect, if mind were alone, and could
understand nothing besides itself. There are, then, many things
outside ourselves, which are useful to us, and are, therefore, to
be desired. Of such none can be discerned more excellent, than
those which are in entire agreement with our nature. For if, for
example, two individuals of entirely the same nature are united,
they form a combination twice as powerful as either of them
singly.

Therefore, to man there is nothing more useful than
man--nothing, I repeat, more excellent for preserving their being
can be wished for by men, than that all should so in all points
agree, that the minds and bodies of all should form, as it were,
one single mind and one single body, and that all should, with
one consent, as far as they are able, endeavour to preserve their
being, and all with one consent seek what is useful to them all.
Hence, men who are governed by reason--that is, who seek what is
useful to them in accordance with reason, desire for themselves
nothing, which they do not also desire for the rest of mankind,
and, consequently, are just, faithful, and honourable in their
conduct.

Such are the dictates of reason, which I purposed thus
briefly to indicate, before beginning to prove them in greater
detail. I have taken this course, in order, if possible, to gain
the attention of those who believe, that the principle that every
man is bound to see