They generally term this second-sight in Irish Taishi-taraughk, and
such as have it Taishatrin, from Taish, which is properly a shadowy
substance, or such naughty, and imperceptible thing, as can only, or
rather scarcely be discerned by the eye; but not caught by the hands:
for which they assigned it to Bugles or Ghosts, so that Taishtar, is
as much as one that converses with ghosts or spirits, or as they
commonly call them, the Fairies or Fairy-Folks. Others call these men
Phissicin, from Phis, which is properly fore-sight, or fore-knowledge.
This is the surest and clearest account of second-sighted men that I
can now find, and I have set it down fully, as if I were transiently
telling it, in your own presence, being curious for nothing but the
verity, so far as I could. What you find improper or superfluous you
can best compendise it, &c,

Thus far this letter, written in a familiar and homely stile, which I
have here set down at length. Meg Mullach, and Brownie mentioned in
the end of it, are two ghosts, which (as it is constantly reported) of
old, haunted a family in Straths-pey of the name of Grant. They
appeared at first in the likeness of a young lass; the second of a
young lad.

Dr. Moulin (who presents his service to you) hath no acquaintance in
Orkney; but I have just now spoken with one, who not only hath
acquaintance in that country, but also entertains some thoughts of
going thither himself, to get me an account of the cures usually
practised there. The Cortex Winteranus, mentioned by you as an
excellent medicine, I have heard it commended as good for the scurvy;
if you know it to be eminent or specific (such as the Peruvian Bark
is) for any disease, I shall be well pleased to be informed by you.