350 BC

                       ON LONGEVITY AND SHORTNESS OF LIFE

                                  by Aristotle

                          translated by G. R. T. Ross

                                 1

  THE reasons for some animals being long-lived and others
short-lived, and, in a word, causes of the length and brevity of
life call for investigation.

  The necessary beginning to our inquiry is a statement of the
difficulties about these points. For it is not clear whether in
animals and plants universally it is a single or diverse cause that
makes some to be long-lived, others short-lived. Plants too have in
some cases a long life, while in others it lasts but for a year.

  Further, in a natural structure are longevity and a sound
constitution coincident, or is shortness of life independent of
unhealthiness? Perhaps in the case of certain maladies a diseased
state of the body and shortness of life are interchangeable, while
in the case of others ill-health is perfectly compatible with long
life.

  Of sleep and waking we have already treated; about life and death we
shall speak later on, and likewise about health and disease, in so far
as it belongs to the science of nature to do so. But at present we
have to investigate the causes of some creatures being long-lived, and
others short-lived. We find this distinction affecting not only entire
genera opposed as wholes to one another, but applying also to
contrasted sets of individuals within the same species. As an instance
of the difference applying to the genus I give man and horse (for
mankind has a longer life than the horse), while within the species
there is the difference between man and man; for of men also some
are long-lived, others short-lived, differing from each other in
respect of the different regions in which they dwell. Races inhabiting
warm countries have longer life, those living in a cold climate live a
shorter time. Likewise there are similar differences among individuals
occupying the same locality.

                                 2

  In order to find premisses for our argument, we must answer the
question, What is that which, in natural objects, makes them easily
destroyed, or the reverse? Since fire and water, and whatsoever is
akin thereto, do not possess identical powers they are reciprocal
causes of generation and decay. Hence it is natural to infer that
everything else arising from them and composed of them should share in
the same nature, in all cases where things are not, like a house, a
composite unity formed by the synthesis of many things.

  In other matters a different account must be given; for in many
things their mode of dissolution is something peculiar to
themselves, e.g. in knowledge and health and disease. These pass
away even though the medium in which they are found is not destroyed
but continues to exist; for example, take the termination of
ignorance, which is recollection or learning, while knowledge passes
away into forgetfulness, or error. But accidentally the disintegration
of a natural object is accompanied by the destruction of the
non-physical reality; for, when the animal dies, the health or
knowledge resident in it passes away too. Hence from these
considerations we may draw a conclusion about the soul too; for, if
the inherence of soul in body is not a matter of nature but like
that of knowledge in the soul, there would be another mode of
dissolution pertaining to it besides that which occurs when the body
is destroyed. But since evidently it does not admit of this dual
dissolution, the soul must stand in a different case in respect of its
union with the body.

                                 3

  Perhaps one might reasonably raise the question whether there is any
place where what is corruptible becomes incorruptible, as fire does in
the upper regions where it meets with no opposite. Opposites destroy
each other, and hence accidentally, by their destruction, whatsoever
is attributed to them is destroyed. But no opposite in a real
substance is accidentally destroyed, because real substance is not
predicated of any subject. Hence a thing which has no opposite, or
which is situated where it has no opposite, cannot be destroyed. For
what will that be which can destroy it, if destruction comes only
through contraries, but no contrary to it exists either absolutely
or in the particular place where it is? But perhaps this is in one
sense true, in another sense not true, for it is impossible that
anything containing matter should not have in any sense an opposite.
Heat and straightness can be present in every part of a thing, but
it is impossible that the thing should be nothing but hot or white
or straight; for, if that were so, attributes would have an
independent existence. Hence if, in all cases, whenever the active and
the passive exist together, the one acts and the other is acted on, it
is impossible that no change should occur. Further, this is so if a
waste product is an opposite, and waste must always be produced; for
opposition is always the source of change, and refuse is what
remains of the previous opposite. But, after expelling everything of a
nature actually opposed, would an object in this case also be
imperishable? No, it would be destroyed by the environment.

  If then that is so, what we have said sufficiently accounts for