Faith and Reason A Lesson from Marco Polo John A. Frantz From: Volume 27, No. 3 April / May 2007 ShareTweet John A. Frantz John A. Frantz practiced medicine from 1946–2006. He taught internal medicine as a Peace Corps volunteer from 1968 to 1970. See more articles This article is available to subscribers only. Subscribe now or log in to read this article.