 He regarded medicine as an interdisciplinary field that was best practiced by utilizing theory, observation, and experimentation in conjunction.Several schools of thought existed within the medical field during Galen's lifetime, the main two being the Empiricists and Rationalists (also called Dogmatists or Philosophers), with the Methodists being a smaller group.The Empiricists emphasized the importance of physical practice and experimentation, or "active learning" in the medical discipline.