Were there a serpent seen with forkéd tongue

That slily glided towards your majesty,

It were but necessary you were waked,

Lest, being suffered in that harmful slumber,

The mortal worm might make the sleep eternal.

Shakespeare, 2 Henry VI., act iii. sc. 2.

Come, thou mortal wretch,

With thy sharp teeth this knot intrinsicate

Of life at once untie.

Id., Antony and Cleopatra, act v. sc. 2.