Select a king and the four knaves and lay the king on the table face
upward. Tell the company that the king is recruiting for the army and
accepts the knave of clubs, which you place on the king's right. The
knave of spades, which you place on the left, he rejects. The knave of
diamonds is accepted and placed on the right. The knave of hearts is
declined, and placed on the left.
Now ask your audience how it is that the king, being in want of
recruits, accepts two and refuses two.
The answer will puzzle those not acquainted with the trick. It is as
follows: Two of the knaves have but one eye each, and are consequently
medically unfit.