I spent the opening day of school this year at DeMatha Catholic High in much the same way I spent the first day of classes exactly 30 years ago; I sat in Dr. Charles E. "Buck" Offutt's British literature class, listening to him explain what his seniors would learn and getting them excited about the journey they would take. I'm the principal of DeMatha now, but for a few minutes I was back in 1975, standing on the brink of adulthood and wondering what the future held. Dr. Offutt's new crop of students couldn't know, as I couldn't then, how many of their lives would be changed by that class.

I have been learning from Dr. Offutt (he is "Buck" to students and faculty alike, but I always think of him as "Dr. Offutt") for 30 of the 51 years he has been teaching at DeMatha. Being in class with Dr. Offutt is like confronting a force of nature -- exciting, dangerous, awe-inspiring. He teaches with a barely suppressed aggression, refusing to tolerate teenage slothfulness. No sloppy statements, no off-the-cuff remarks, no casual preparation and no excuses. Go to the text; make inferences that can be supported; present conclusions lucidly; and connect everything you learn to what you already know.

Assigning us to read challenging pieces of literature, Dr. Offutt pushed us to penetrate their metaphors and unravel their allusions, to understand symbolic language and consider deeper meanings. I struggled until we were assigned Robert Browning's chilling poem "My Last Duchess." I couldn't quite believe that I was reading the poem correctly. Was the narrator really a sadist who'd had his wife murdered? Was he the control freak that he seemed to be? He was. And, suddenly, I found myself looking at the world with new eyes and feeling as if I were part of an exclusive club. Meaning was everywhere, in every gesture and word.

Until I took Dr. Offutt's class, I was an underachieving student, but I left that class determined never to underachieve again. He not only taught me to think, he convinced me, as much by example as words, that it was my moral obligation to do so and to serve others. I teach others because he taught me.

Neither of us could know how our relation-ship would evolve over the years. When I came back to DeMatha to teach English in 1981, I worked for Dr. Offutt, the department chair. My discussions with him as he mentored me were like graduate seminars in adolescent development, classroom management, pedagogical technique and school leadership.

After several years, I was named department chair, and our relationship shifted again. I thought that it might be awkward chairing the department, since all of my former English teachers were still there, but Dr. Offutt supported me throughout. He knew when to give me advice about curriculum, texts and personnel, and when to let me chart my own course.

In 1997, I needed his advice about leaving DeMatha to become principal at the Bullis School. We met at school one Saturday morning to talk about the job offer. If he had asked me to stay at DeMatha, I might have. Instead, he encouraged me to seize the new opportunity. As I had done when I went away to college, I wrote to him each year from my new job, thanking him for the role he had played in my life.

Five years ago, I became the principal of DeMatha, replacing John Moylan, a legendary school leader. Once again, Dr. Offutt was there for me, letting me know that I could count on him as I tried to fill such big shoes. I've learned from Dr. Offutt that great teachers have an inexhaustible wealth of lessons to teach. Even if his students don't know it yet, I know how fortunate they are; I'm still one of them.

Daniel McMahon is principal and teaches world literature at DeMatha Catholic High School in Hyattsville.