Q. 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 sun, and heat naturally causes putrefaction; therefore the matter of hair doth putrefy, and in consequence they are quickly peeled.

Q. Why do men get bald, and trees let fall their leaves in winter?  A. The want of moisture is the cause in both, which is proved by a man’s becoming bald through venery, because by that he lets forth his natural humidity and heat; and by that excess in carnal pleasure the moisture is consumed which is the nutriment of the hair.  Thus, eunuchs and women do not grow bald, because they do not part from this moisture; and therefore eunuchs are of the complexion of women.