Haroun summoned Sir Philip Derval, and said to him,--

"Depart to Damascus. In that city the Pestilence has appeared. Go
thither thou, to heal and to save. In this casket are stored the surest
antidotes to the poison of the plague. Of that essence, undiluted and
pure, which tempts to the undue prolongation of soul in the prison of
flesh, this casket contains not a drop. I curse not my friend with so
mournful a boon. Thou hast learned enough of my art to know by what
simples the health of the temperate is easily restored to its balance, and
their path to the grave smoothed from pain. Not more should Man covet
from Nature for the solace and weal of the body. Nobler gifts far than
aught for the body this casket contains. Herein are the essences which
quicken the life of those duplicate senses that lie dormant and coiled in
their chrysalis web, awaiting the wings of a future development,--the
senses by which we can see, though not with the eye, and hear, but not by
the ear. Herein are the links between Man's mind and Nature's; herein are
secrets more precious even than these,--those extracts of light which
enable the Soul to distinguish itself from the Mind, and discriminate the
spiritual life, not more from life carnal than life intellectual. Where
thou seest some noble intellect, studious of Nature, intent upon Truth,
yet ignoring the fact that all animal life has a mind and Man alone on the
earth ever asked, and has asked, from the hour his step trod the earth,
and his eye sought the Heaven, 'Have I not a soul; can it perish?'--there,
such aids to the soul, in the innermost vision vouchsafed to the mind,
thou mayst lawfully use. But the treasures contained in this casket are
like all which a mortal can win from the mines he explores,--good or ill
in their uses as they pass to the hands of the good or the evil. Thou
wilt never confide them but to those who will not abuse! and even then,
thou art an adept too versed in the mysteries of Nature not to
discriminate between the powers that may serve the good to good ends, and