Why would you take poison as medicine? health.howstuffworks.com. 13/08/08. Humans have used poison to dispatch their enemies and rivals for a very long time. Some of history’s greatest figures met their ends through poisoning. For publicly criticizing the ruling class, the Greek philosopher Socrates was executed in 399 B.C. by being made to drink a cup filled with poison hemlock. Hemlock depresses the central nervous system, leading to slowed respiration and pulse before the body shuts down.[ Read more and watch video ]. See related article in same page: Poison as an Antidote.