ransforms our food and the
tissues and the humours of our system. And by the coalition of _Prana_
and other airs, a reaction (combination) ensues, and the heat generated
thereby is known as the internal heat of the human system which causes
the digestion of our food. The _Prana_ and the _Apana_ air are
interposed within the _Samana_ and the _Udana_ air. And the heat
generated by their coalition causes the growth of the body (consisting
of the seven substances, bones, muscles, &c). And that portion of its
seat extending to as far as the rectum is called _Apana_; and from that
arteries arise in the five airs _Prana_, &c. The _Prana_ air, acted on
by the heat strikes against the extremity of the _Apana_ region and then
recoiling, it reacts on the heat. Above the navel is the region of
undigested food and below it the region of digestion. And the _Prana_
and all other airs of the system are seated in the navel. The arteries
issuing from the heart run upwards and downwards, as also in oblique
directions; they carry the best essence of our food, and are acted upon
by the ten _Prana_ airs. This is the way by which patient _Yogins_ who
have overcome all difficulties, and who view things with an impartial
and equal eye, with their souls seated in the brain, find the Supreme
Spirit, the _Prana_ and the _Apana_ airs are thus present in the body of
all creatures. Know that the spirit is embodied in corporeal disguise,
in the eleven allotropous conditions (of the animal system), and that
though eternal, its normal state is apparently modified by its
accompaniments,--even like the fire purified in its pan,--eternal, yet
with its course altered by its surroundings; and that the divine thing
which is kindred with the body is related to the latter in the same way
as a drop of water to the sleek surface of a lotus-leaf on which it
rolls. Know that _sattwa, rajas_ and _tamas_, are the attributes of all
life and that life is the attribute of spirit, and that the latter again
is an attribute of the Supreme Spirit. Inert, insensible matter is the
seat of the living principle, which is active in itself and induces
activity in others. That thing by which the seven worlds are incited to
action is called the most high by men of high spiritual insight. Thus in
all these elements, the eternal spirit does not show itself, but is
perceived by the learned in spiritual science by reason of their high
and keen perception. A pure-minded person, by purific