PhD in Classics, Stanford University, in the course of which program I read a bit of linguistics, of which I liked the functionalists best (Chafe, Halliday, Hasan, Givon, etc). Since then all my understanding of language comes from teaching ESL to French people, especially University students. I can say that this last experience has taught me more abut language than the Phd in Classics from Stanford, or reading the linguists named above. There is nothing like teaching ESL to talented students to teach you about language in general, as others on this site have commented.