It has been already mentioned in the law against witches, that they are supposed to take up dead bodies to use in enchantments, which was confessed by the woman whom king James examined, and who had of a dead body that was divided in one of their assemblies, two fingers for her share.  It is observable that Shakespeare, on this great occasion, which involves the fate of a king, multiplies all the circumstanaces of horror.  The babe, whose finger is used, must be strangled in its birth; the grease must not only be human, but must have dropped from a gibbet, the gibbet of a murderer; and even the sow, whose blood is used, must have offended nature by devouring her own farrow.  These are touches of judgment and genius.

  And now about the cauldron sing—­
  Black spirits and white,
     Blue spirits and grey,
  Mingle, mingle, mingle,
  You that mingle say.

And in a former part,

—­weyward sisters, hand in hand,—­ Thus do go about, about.  Thrice to thine, and thrice to mine.  And thrice again to make up nine!

These two passages I have brought together, because they both seem subject to the objection of too much levity for the solemnity of enchantment, and may both be shewn, by one quotation from Camden’s account of Ireland, to be founded upon a practice really observed by the uncivilised natives of that country:  “When any one gets a fall, says the informer of Camden, he starts up, and, turning three times to the right, digs a hole in the earth; for they imagine that there is a spirit in the ground, and if he falls sick in two or three days, they send one of their women that is skilled in that way to the place, where she says, I call thee from the east, west, north, and south, from the groves, the woods, the rivers, and the fens, from the fairies red, black, white.”  There was likewise a book written before the time of Shakespeare, describing, amongst other properties, the colours of spirits.

Many other circumstances might be particularised, in which Shakespeare has shown his judgment and his knowledge.

IV.i.53 (489,6) yesty waves] That is, foaming or frothy waves.

IV.i.88 (491,1) the round/And top of sovereignty?] This round is that part of the crown that encircles the head.  The top is the ornament that rises above it.

IV.i.95 (492,3) Who can impress the forest] i.e. who can command the forest to serve him like a soldier impress’d. (1773)

IV.i.97 (492,4) Rebellious head, rise never] Mr. Theobald, who first proposed this change ["head” for “dead”] rightly observes, that head means host, or power.

  —­Douglas and the rebels met,
  A mighty and a fearful head they are.

And again,

  His divisions—­are in three heads.

IV.i.113 (493,6) Thy crown does sear mine eye-balls] The expression of Macbeth, that the crown sears his eye-balls, is taken from the method formerly practised of destroying the sight of captives or competitors, by holding a burning bason before the eye, which dried up its humidity.  Whence the Italian, abacinare, to blind.