Holmes went to Paris to further his medical studies in 1833, because the French were leading the way in basing medicine on hard scientific facts and new tools, such as the stethoscope. He took full advantage of all that Paris had to offer in the classroom, clinics, and dissecting sites. Pierre Charles Alexandre Louis, who railed against worthless therapies (e.g., bloodletting) and unsubstantiated theorizing, was his favorite teacher. Holmes agreed with Louis about medical quackery and learning more about phrenology while in Paris, where some of his teachers embraced it, while others damned it. Many French physicians were then publishing books on phrenology, and Paris was now home to a very active phrenological society, the Société Phrénologique. Some of the Americans he was with also visited phrenology shops. For example, John Collins Warren’s son bought books and specimens for his father while there. Yet Holmes was still not ready to present his own opinions about the new science in print. He did not even bring it up in private letters to his parents, though he did mention finding charlatanism running rampant in Britain, which he visited. He did not elaborate.