In 1 Henry IV. (i. 1. 87), the King, contrasting the gallant Hotspur with his own profligate son, exclaims:
"O that it could be proved
That some night-tripping fairy had exchang'd
In cradle-clothes our children where they lay,
And call'd mine Percy, his Plantagenet!
Then would I have his Harry, and he mine."
The belief in the "evil eye" was another superstition prevalent in Shakespeare's day, as it had been from the earliest times. It dates back to old Greek and Roman days, being mentioned by Theocritus, Virgil, and other classical writers. In Turkey passages from the Koran used to be painted on the outside of houses as a protection against this malignant influence of witches, who were supposed to cause serious injury to human beings and animals by merely looking at them.
Thomas Lupton, in his Book of Notable Things (1586) says: "The eyes be not only instruments of enchantment, but also the voice and evil tongues of certain persons." Bacon, in one of his minor works, remarks: "It seems some have been so curious as to note that the times when the stroke or percussion of an envious eye does most hurt are particularly when the party envied is beheld in glory and triumph."
Robert Heron, writing in 1793 of his travels in Scotland, says: "Cattle are subject to be injured by what is called an evil eye, for some persons are supposed to have naturally a blasting power in their eyes, with which they injure whatever offends or is hopelessly desired by them. Witches and warlocks are also much disposed to wreak their malignity on cattle.... It is common to bind into a cow's tail a small piece of mountain-ash wood, as a charm against witchcraft."
As recently as August, 1839, a London newspaper reports a case in which a woman was suspected of the evil eye by a fellow-lodger merely because she squinted.