Why doth man, above all other creatures, wax hoary and gray? A.
Because man hath the hottest heart of all living creatures; and
therefore, nature being most wise, lest a man should be suffocated
through the heat of his heart, hath placed the heart, which is most hot,
under the brain, which is most cold; to the end that the heat of the
heart may be tempered by the coldness of the brain; and contrariwise,
that the coldness of the brain may be qualified by the heat of the
heart; and thereby there might be a temperature in both. A proof of this
is, that of all living creatures man hath the worst breath when he comes
to full age. Furthermore, man doth consume nearly half his time in
sleep, which doth proceed from the great excess of coldness and moisture
in the brain, and from his wanting natural heat to digest and consume
that moisture, which heat he hath in his youth, and therefore, in that
age is not gray, but in old age, when heat faileth; because then the
vapours ascending from the stomach remain undigested and unconsumed for
want of natural heat, and thus putrefy, on which putrefaction of humours
that the whiteness doth follow, which is called grayness or hoariness.
Whereby it doth appear, that hoariness is nothing but a whiteness of
hair, caused by a putrefaction of the humours about the roots of the
hair, through the want of natural heat in old age. Sometimes all
grayness is caused by the naughtiness of the complexion, which may
happen in youth: sometimes through over great fear and care as appeareth
in merchants, sailors and thieves.

Q. Why doth red hair grow white sooner than hair of any other colour? A.
Because redness is an infirmity of the hair; for it is engendered of a
weak and infirm matter, that is, of matter corrupted with the flowers of
the woman; and therefore it waxes white sooner than any other colour.

Q. Why do wolves grow grisly? A. To understand this question, note the
difference between grayness and grisliness; grayness is caused through
defect of natural heat, but grisliness through devouring and heat. The
wolf being a devouring beast, he eateth gluttonously without chewing,
and enough at once for three days; in consequence of which, gross
vapours engendered in the wolf's body, which cause grisliness. Grayness
and grisliness have this difference; grayness is only in the head, but
grisliness all over the body.

Q. Why do horses grow grisly and gray? A. Because they are for the most
part in the s