Annotation: Hemlock, Keats' Ode to A Nightingale

My heart aches, and a drowsy numbness pains

My sense, as though of hemlock I had drunk

The Death of Socrates, by Jacques-Louis David

Hemlock, Conium Maculatum

Hemlock was used in Ancient Greece to execute condemned prisoners. One such was the philosopher Socrates. Through his poetry we know that Keats was interested in the Classical world, I believe his reference to the drowsy numbness of hemlock is based on Plato's description of Socrates' death in Phaedo:

The man...examined his feet and legs, then pinched his foot hard and asked if he felt it. He said "No"; then after that, his thighs; and passing upwards in this way he showed us that he was growing cold and rigid. And then again he touched him and said that when it reached his heart, he would be gone. 

Source
"Conium." Wikipedia, the free encyclopedia. N.p., n.d. Web. 27 May 2012. <http://en.wikipedia.org/wiki/Conium>