I find thee apt,
And duller shouldst thou be than the fat weed
That roots itself in ease on Lethe wharf,
Wouldst thou not stir in this.

– William Shakespeare

Hamlet, Act 1, Scene 5. The Ghost is pleased with Hamlet’s response to his command for revenge. If he failed to act he would be as lazy as the weed that grows on the banks of Lethe, the Greek river of forgetfulness.