Shakespeare often uses similes to heighten the play's sense of emotion. In Act 3, Scene 3, Gonzalo uses a simile to compare guilt to poison:
All three of them are desperate. Their great guilt,
Like poison given to work a great time after,
Now 'gins to bite the spirits. I do beseech you
That are of suppler joints, follow them swiftly
And hinder them from what this ecstasy
May now provoke them to
In other words, guilt works like a poison in the body; it begins to wear on one's conscience as a toxic substance might degrade one's body. Those who remain lively and energetic must stop the others from doing bad things. Gonzalo is quite old, so it's reasonable to assume that by those "of suppler joints" he refers to the other, younger, and more agile characters in the play. What's more, a new facet of Gonzalo's character emerges in this simile. He sounds old and wise here, as his observation about guilt provides some insight into the depth of his mind. The poison simile extends across six lines, which gives it greater power and shows that it was more than just a passing thought or bit of wordplay.