I have been dreading this semester. Bill Mallard, my colleague in historical studies at Candler School of Theology, is retiring at the end of the year. Together he and I have team taught the first semester of the History of Christian Thought each fall for 21 years. It is hard for me to imagine what the autumns will be like now.

Ancient Greek philosophers regarded change as a very bad thing. From their perspective, it can only lead to degeneration and death. In the fourth century the optimistic Christian bishop Gregory of Nyssa attempted to take this theme of change and stand it on its head. It is a good thing that we are changeable, he said, because although death is real, change gives us the chance to grow continually toward God in love.

When I think about my friend and colleague's retirement, it is hard to hold on to Gregory's affirmation. I do not want our class to end. Over the years we have become partners, collaborators, mutual supporters, fellow workers and co-teachers. Together we have worked at our class until we have made it just what we want it to be. Though we do not always share a common theology, we share common goals in teaching the history of Christian thought to seminary students. We love to teach our class, and we love to teach it together.

Teaching together wasn't always like this. When I arrived at Candler 21 years ago, I had mostly taught Semitic languages in very small classes. I loved the early church and was convinced that knowledge of it is an immense resource for modern Christians, but I didn't have a clue about how to offer a course. I couldn't construct an hour-and-20-minute lecture. Though I had done a dissertation in the field, I had taken very few classes in Christian thought. I was painfully shy, excruciatingly aware of my limitations, defensive, afraid of what were then mostly male, often hostile students. I couldn't guess what those students expected or needed.

On the other hand, Bill had been teaching the course for years. He was a fabulously popular lecturer, full of intelligence, energy, warmth, patience, fun and Christian commitment. He also knew the names and personal histories of most of the students—140 or so—by mid-semester.

My inexperience coupled with his seasoned gifts did not make for a great team. In those first years I think we hardly knew what to do with each other. I couldn't figure out how our very different theological perspectives—his, basically Augustinian; mine, mainly formed by the Eastern Christian tradition—could work together without undermining each other. Neither of us understood each other's theology anyway. As for my problems in teaching, he didn't make suggestions; indeed, we rarely had conversations about teaching at all.

Nevertheless, after six or seven years we found that we had learned to teach together. Gradually, we came to understand each other's theological positions and were able to show the students how these positions fit or didn't fit with each other. I paid close attention to Bill's way of lecturing and learned how to put a lecture together. Realizing at last that he had the same patience and tolerance with me that he had with the students, I lost my fear of making a fool of myself and learned instead to love and then to enjoy our students. We came to share the same teaching goals and the same convictions about how to reach those goals.

Over the years I believe I have learned to be a good teacher, but it is only recently that I have realized how much of what I know has come not from what Bill has said but from what he has modeled about teaching and the spiritual life. In this regard, I recall two of my favorite passages in the Sayings of the Desert Fathers. The first is from Amma Syncletia:

It is dangerous for anyone to teach who has not first been trained in the "practical" life. For if someone who owns a ruined house receives guests there, he does them harm because of the dilapidation of his dwelling. It is the same in the case of someone who has not first built an interior dwelling; he causes loss to those who come.

By being who he is, Bill has taught me the importance both of building that "interior dwelling" for myself and, as a teacher, of helping the students learn to build their own houses.

My other favorite saying is from Amma Theodora, who describes the "practical" building blocks of the interior dwelling of a teacher of Christianity:

A teacher ought to be a stranger to the desire for domination, vainglory and pride; one should not be able to fool him [or her] by flattery, nor blind him [or her] by gifts, nor conquer him [or her] by the stomach, nor dominate . . . by anger; but he [or she] should be patient, gentle and humble as far as possible; he [or she] must be tested and without partisanship, full of concern and a lover of souls.

As a lover of souls, my good colleague has taught me most of what I know about teaching by embodying these virtues.

That I have been able to learn such important things proves Gregory of Nyssa to be right about change. But I still hate it.