Just as a body which has a leg too long, or
which is unsymmetrical in some other respect, is an unpleasant
sight, and also, when doing its share of work, is much distressed
and makes convulsive efforts, and often stumbles through
awkwardness, and is the cause of infinite evil to its own self-in
like manner we should conceive of the double nature which we call
the living being; and when in this compound there is an
impassioned soul more powerful than the body, that soul, I say,
convulses and fills with disorders the whole inner nature of man;
and when eager in the pursuit of some sort of learning or study,
causes wasting; or again, when teaching or disputing in private
or in public, and strifes and controversies arise, inflames and
dissolves the composite frame of man and introduces rheums; and
the nature of this phenomenon is not understood by most
professors of medicine, who ascribe it to the opposite of the
real cause. And once more, when body large and too strong for the
soul is united to a small and weak intelligence, then inasmuch as
there are two desires natural to man,-one of food for the sake of
the body, and one of wisdom for the sake of the diviner part of
us-then, I say, the motions of the stronger, getting the better
and increasing their own power, but making the soul dull, and
stupid, and forgetful, engender ignorance, which is the greatest
of diseases. There is one protection against both kinds of
disproportion:-that we should not move the body without the soul
or the soul without the body, and thus they will be on their
guard against each other, and be healthy and well balanced. And
therefore the mathematician or any one else whose thoughts are
much absorbed in some intellectual pursuit, must allow his body
also to have due exercise, and practise gymnastic; and he who is
careful to fashion the body, should in turn impart to the soul
its proper motions, and should cultivate music and all
philosophy, if he would deserve to be called truly fair and truly
good. And the separate parts should be treated in the same
manner, in imitation of the pattern of the universe; for as the
body is heated and also cooled within by the elements which enter
into it, and is again dried up and moistened by external things,
and experiences these and the like affections from both kinds of
motions, the result is that the body if given up to motion when
in a state of quiescence is overmastered and perishes; but if any
one, in imitation of that which we call the foster-mother and
nurse of the universe, will not allow the body ever to be
inactive, but is always producing motions and agitations through
its whole extent, which form the natural defence against other
motions both internal and external, and by moderate exercise
reduces to order according to their affinities the particles and
affections which are wandering about the body, as we have already
said when speaking of the universe, he will not allow enemy
placed by the side of enemy to stir up wars and disorders in the
body, but he will place friend by the side of friend, so as to
create health.
Now of all motions that is the best which is produced in a
thing by itself, for it is most akin to the motion of thought and
of the universe; but that motion which is caused by others is not
so good, and worst of all is that which moves the body, when at
rest, in parts only and by some external agency. Wherefore of all
modes of purifying and reuniting the body the best is gymnastic;
the next best is a surging motion, as in sailing or any other
mode of conveyance which is not fatiguing; the third sort of
motion may be of use in a case of extreme necessity, but in any
other will be adopted by no man of sense: I mean the purgative
treatment of physicians; for diseases unless they are very
dangerous should not be irritated by medicines, since every form
of disease is in a manner akin to the living being, whose complex
frame has an appointed term of life. For not the whole race only,
but each individual-barring inevitable accidents-comes into the
world having a fixed span, and the triangles in us are originally
framed with power to last for a certain time, beyond which no man
prolong his life. And this holds also of the constitution of
diseases; if any one regardless of the appointed time tries to
subdue them by medicine, he only aggravates and multiplies them.
