e.
On leaving the body it is cooled and drives round the air which it
displaces through the pores into the empty lungs. This again is in turn
heated by the internal fire and escapes, as it entered, through the
pores.

The phenomena of medical cupping-glasses, of swallowing, and of the
hurling of bodies, are to be explained on a similar principle; as also
sounds, which are sometimes discordant on account of the inequality
of them, and again harmonious by reason of equality. The slower sounds
reaching the swifter, when they begin to pause, by degrees assimilate
with them: whence arises a pleasure which even the unwise feel, and
which to the wise becomes a higher sense of delight, being an imitation
of divine harmony in mortal motions. Streams flow, lightnings play,
amber and the magnet attract, not by reason of attraction, but because
'nature abhors a vacuum,' and because things, when compounded or
dissolved, move different ways, each to its own place.

I will now return to the phenomena of respiration. The fire, entering
the belly, minces the food, and as it escapes, fills the veins by
drawing after it the divided portions, and thus the streams of nutriment
are diffused through the body. The fruits or herbs which are our daily
sustenance take all sorts of colours when intermixed, but the colour of
red or fire predominates, and hence the liquid which we call blood is
red, being the nurturing principle of the body, whence all parts are
watered and empty places filled.

The process of repletion and depletion is produced by the attraction
of like to like, after the manner of the universal motion. The external
elements by their attraction are always diminishing the substance of
the body: the particles of blood, too, formed out of the newly digested
food, are attracted towards kindred elements within the body and so fill
up the void. When more is taken away than flows in, then we decay; and
when less, we grow and increase.

The young of every animal has the triangles new and closely locked
together, and yet the entire frame is soft and delicate, being newly
made of marrow and nurtured on milk. These triangles are sharper than
those which enter the body from without in the shape of food, and
therefore they cut them up. But as life advances, the triangles wear out
and are no longer able to assimilate food; and at length, when the bonds
which unite the triangles of the marrow become undone, they in turn
unloose the bonds of