"A lot of information from various sources comes across my desk and sometimes I get to feeling that I know all there is to know on the subject.  My school sent me to your workshop and it was well worth the particularly nasty two-hour drive that night.  I came home with two pages of notes and began incorporating the information I got from you into my own workshops.  What impressed me the most was that I actually learned a great deal from you that I didn't know or hadn't thought of before."