Don’t believe me because you see me as your teacher. Don’t believe me because others do. And don’t believe anything because you’ve read it in a book, either. Don’t put your faith in reports or tradition or hearsay or the authority of religious leaders or texts. Don’t rely on mere logic or inference or appearances or speculation. Know for yourselves that certain things are unwholesome and wrong. And when you do, then give them up. And when you know for yourselves that certain things are wholesome and good, then accept them and follow them.
Quoted by Steve Hagen in Buddhism Is Not What You Think and relevant to teachers everywhere.