My mobile phone rang early one Sunday morning in October 2013. “It is Helena calling from Moscow,” the voice said. “My husband, David, was run over by a tractor-trailer while riding his bike in Jerusalem. He is in very critical condition. I am returning to Israel.” David’s son Eli called later and, whispered, in a broken voice, “We are losing him.The doctors at Hadassah Hospital can’t control his massive bleeding.”I had met David Kazhdan 37 years earlier, at Rabbi Joseph Soloveitchik’s Sunday morning Talmud class at the Maimonides School in Brookline, Massachusetts. I had just started my postdoctoral work in vascular biology at Harvard Medical School. I was immersed in a world of cutting-edge science, of empiricism. But on the weekends I left that world behind to engage with the preeminent rabbi and legendary philosophical scholar who promoted building bridges between traditional Orthodox Judaism and the modern world. And it was in “the Rav’s” class that I met David.David had grown up in an atheist family in Moscow. The son of a renowned scholar of the Byzantine empire, David’s reputation as a prodigy was well known in the Boston Jewish community. He had emigrated with his young family in 1975 and joined the Harvard mathematics faculty. In 1977, he was appointed a full professor and became known for his important contributions to group theory, a cornerstone of mathematics with applications in fields such as physics, quantum theory, and computer science.Despite his atheist background, in his early 20s David discovered his Jewish roots, became observant, and taught himself Hebrew. He was a source of inspiration for the early refuseniks in Moscow. By the time we met, he had vast knowledge of both Hebrew and Aramaic Jewish texts. The Rav enjoyed conversing with him and was amazed by his brilliance and his dedication to Jewish studies.On a Sunday morning in 1977, following the Rav’s Talmud class, David approached me. “Do you want to learn together?” he asked, in a pronounced Russian accent. I said yes, and we set up a daily schedule and started studying b’chevruta, literally “in friendship,” as partners.Over the following decades, we covered various topics and texts. Bible, tractates of Talmud, the writings of Maimonides and of Nachmanides, other philosophical texts. Initially, these daily sessions took place in the early mornings at the Tolner synagogue in Brookline, although at times the location changed: David’s academic office in Cambridge; Einstein’s Institute for Advanced Studies in Princeton, where David was a visiting scholar studying string physics; our respective homes.The early morning sessions at the Tolner shul were very memorable for us, especially during the cold Boston winters. In the dark of night, David and I would gingerly make our way through high piles of snow and ice into the empty Tolner Beit Midrash, warm and, once lit, very inviting. There was total silence. Surrounded by a library of ancient texts, we would study for one hour by a long wooden table in solitude, deciphering ancient Aramaic and Hebrew texts.Precisely 10 minutes before the scheduled start of the morning prayers, we would hear a key turning in the synagogue’s old lock. We could set our watches by this daily sound. The Tolner Rebbe professor Isadore Twersky of Harvard University (the Rav’s son-in law) would enter. Once the morning services commenced, David and I would stand next to each other in prayer. Then we would head to our respective offices, David to his abstract studies in the math department, I to the patients, test tubes, and animals at the medical-school complex.Following my family’s move to the New York area in 1985, we continued our daily study via phone or Skype.These calls were made from various locales in the United States, Europe, Israel, or wherever David’s or my professional and family schedules placed us. In these learning sessions, there was no banter, almost no mention of family life, professional, or socio-political issues. But we were so attuned to slight nuances in our voices, little tremors or hesitations, that when something unusual had happened, we would recognize it in the first few seconds of the call. And then the conversation would turn to expressions of understanding, support, concern, and identification.Beyond this daily interaction solely dedicated to learning, we shared many memorable personal experiences. There were smachot, joyous ceremonies celebrating personal and professional milestones. There was walking together forlornly behind the coffin at the Rav’s funeral. Or raising funds for an organization supporting Russian Jewry. Just taking long Sunday family walks around Walden Pond in a forest outside Boston. Or having Shabbat meals. Often, we spoke of the intersection of science and religion and the importance of secular education in Jewish day schools.Major changes took place in our lives. The births of children and grandchildren, the passing of our parents, David’s and his family’s move to Jerusalem, academic and professional advancements highlighted by David’s chairmanship of math at Harvard, his MacArthur “genius” award, the Israel Prize for mathematics.And for many years, on the first day of Rosh Hashanah, we met at the reservoir by the Maimonides School for tashlich. We walked around the beautiful, mile-long body of water as the sun was slowly setting, as if to review and celebrate the passing of another year of learning, deep friendship, and its impact on the texture of our lives.Getting that phone call—the thought of losing David was devastating and paralyzing.On Monday, Oct. 7, 2013, David’s son Eli emailed: “… the bleeding is under control, the CT of the head shows that all is good up there…” Days later, he wrote: “With some trepidation, it seems that we have indeed turned a very important corner—and my father’s condition can be carefully and optimistically defined as ‘serious but stable.’”With his wife’s love and dedication, and the steadfast care and support of his doctors, family, friends, and colleagues worldwide, against all odds, David survived.Weeks later, David regained consciousness. He was still gravely ill and in the ICU, but we resumed our learning. I had forgotten where we had left off in our studies, but David remembered exactly what we were up to. David had a turbulent recovery course that required many surgeries and close to a yearlong hospitalization. And, still, we kept studying.Three years after this horrific accident, David continues to be challenged by the physical consequences of his injuries. But he courageously perseveres.In Deuteronomy 29:3, Moses says, “But Hashem did not give you a heart to know, or eyes to see or ears to hear until this day.” The Talmud derives from this verse that only after 40 years does a disciple fully appreciate the greatness of his teacher (Avodah Zarah 5b). As the role of each participant in chevruta alternates between teacher and student, this assertion describes my relationship to David, too. Over four decades of daily learning, whether for minutes or an hour, our chevruta morphed from a pure intellectual religious experience, an attempt to cultivate creativity and knowledge in diverse areas of Talmud, halacha, and philosophy, to become our shared faith-based metronome, the pacemaker that takes us back to our youth and remains oscillating and firing through the trials and tribulations of daily life. What we study—Maimonides, Nachmanides’ insightful commentaries on the Bible, the complex laws of yibbum (levirate marriage), Tractate Eruvin, dealing with the various private and public domains on Shabbat—is now of secondary significance. Our faith-based, text-anchored relationship reminds us, on a daily basis, that we are not alone. It is about being there. Every day.Maimonides defines the friend-for-virtue, haver le-de’ah, as a friend who shares a common desire and goal. Such friends seek each other’s aid in the attainment of this ideal. In an era when friendship can mean merely sharing digital and graphic social content over the internet, David’s and my daily interaction is anchored by the common goal: a rhythmic injection of transcendent religious significance into our daily life through an intellectual dialogue. In our web-based society, when one can “friend” or “unfriend” someone with a click on Facebook, the learning b’chevruta can serve as a model of profound everlasting friendship.Perhaps our most dramatic learning session took place months after David’s discharge from the hospital. The Skype call that David initiated was of poor quality, with a very noisy background. “You must have many guests?” I said. “No,” he answered in an unruffled voice. “I am in the emergency room of Hadassah Hospital, being evaluated for high fever and sepsis and I have a few minutes now. Let’s learn.” And we did.***Like this article? Sign up for our Daily Digest to get Tablet Magazine’s new content in your inbox each morning.