Glimpsing the Infinite in the Microscopic

John Loike Tradition Online | October 6, 2021

With the conclusion today of Shiva for R. Dr. Moshe D. Tendler zt”l, we present the third and final installment in our series exploring his legacy. (Read the first two essays here; visit R. Tendler’s archived TRADITION articles here.)

Time Magazine (May 31, 1963) – Click to enlarge

Rabbi Dr. Moshe Tendler zt”l was an outstanding rabbinic figure and posek whose dignity, wisdom, vision, and courage impacted his congregants and students in Monsey and in Yeshiva University, and in Jewish communities around the world, for the last seven decades. He was a distinguished Rav and a respected biomedical scientist, a combination as unusual today as it was when he embarked upon this twin career.

R. Tendler received rabbinical ordination from Yeshiva University in 1949 and his Ph.D. in 1957 in microbiology from Columbia University. His brilliant understanding of Torah and biomedical science enabled him to establish critical halakhic guidelines in those fields from the 1950s until the present day. In 1953, for example, he began teaching a course at Yeshiva College on Medical Ethics that led to the publication of Medical Ethics: A Compendium of Jewish Moral, Ethical and Religious Principles – a book that became the standard Jewish text distributed to many hospitals and Jewish organizations. He was uniquely positioned to play a decisive role in this field through his mastery of complex scientific concepts, from a research and practical perspective, and his ability to apply those as the foundation for rendering important halakhic responsa. He continued to establish guidelines in Jewish medical ethics throughout his life that have impacted both the care of patients and physician’s responsibilities toward their patients. His halakhic analyses and perspectives also influenced many leading rabbis, perhaps most significantly his father-in-law, Rav Moshe Feinstein zt”l, and his rulings relating to science, medicine, and halakha.

I had the privilege of being R. Tendler’s student and of co-authoring with him over 25 articles on halakha and bioethics over the past 20 years. I would like to share three reminiscences about my special experiences with him that provide a glimpse into things I learned about this great man as a Torah scholar, scientist, and posek.

As has been widely recounted since his passing, his sense of humor was as legendary as his ability to marshal it in the use of gently conveying life lessons. I once asked him to explain the concept of gilgul neshamot (transmigration of the souls) as presented in the Alshikh’s commentary on the Book of Job. R. Tendler responded that he could not give me a short explanation at that moment, but told me to be patient. He informed me that the well-known Gemara that one should not delve into kabbalistic thoughts until reaching the age of 50 (Hagiga 13a) contains a misprint – it should read “until one is one hundred and fifty.” His musar was not lost on me, and I understood that the time was not (yet) right for my wading into the mystical realms. 

The second story reflects R. Tendler’s philosophy regarding topics we chose to write about together. He valued innovative scientific discoveries and their impact on halakha. His profound understanding of science enabled him to tackle the halakhic complexities and the challenges of new technologies. He possessed insatiable curiosity and loved to learn about new scientific discoveries, in their own right, and consider together how halakha needed to respond to these innovations. 

I recall the first time we discussed the emerging science of stem cell technology that would allow scientists to transform skin cells (fibroblasts) into any specialized tissue including sperm or eggs. One halakhic challenge was related to the idea of generating a child using stem cells and without the use of sperm or eggs. Before considering the halakhic ramifications he asked that I provide him with the most significant peer-reviewed articles on the topic. He read everything I suggested and then supplemented the bibliography with additional relevant material he found on his own. 

He then cited the case of Rav, who spent eighteen months among the shepherds studying treifot (Sanhedrin 5b). Next, he described how R. Zeira was reluctant to rule on issues of family purity without requisite knowledge of the physiology involved (Nidda 20b). For R. Tendler these Talmudic figures served as models of how to paskin on science-based issues. Before he would even begin to engage in the halakhic discussions, he needed to fully grasp all the details of the technologies. 

Many times R. Tendler asked me to demonstrate how certain new technologies were used in my lab. Observing actual experiments and medical situations were essential to his thinking about the halakhic ramifications of these technologies. By means of illustration, he would tell me about his many “outings” with his “shver,” Rav Moshe, to observe patients in the ICU so that the posek ha-dor could fully understand the medical parameters of a comatose patient before issuing his halakhic directive on brain death.

R. Tendler followed Rav Moshe’s strict position concerning abortion, but, when compelled to offer a specific psak to a pregnant woman, he would always speak to her and her physicians about the particulars of the case. Based on their statements he would at times allow termination of a fetus. He emphasized that halakha has two parameters: general halakhic principles and also how to apply these principles to a specific case. The latter parameter required him to speak with both the patient and the physician before rendering a decision.

Only when a case resided in the realm of the fully theoretical was R. Tendler hesitant to issue a halakhic decision. For example, stem cell technology could be used to generate an embryo from three parents. Among the very many imaginable future questions this will present, he told me that he was not prepared to determine the kahuna state of a child generated from stem cells obtained from male Kohen and Yisrael donors. Only when the situation moved from the theoretical to a real case would he paskin.

Finally, I wish to share a memory that relates to his holistic approach to Torah and science. When R. Tendler first began teaching biology, he would have his students look into their microscopes to view slides of a human cell and ask them to describe what they observed. One student would say that he saw the nucleus of the cell, another would comment on the lysosomes, and a third would describe the structure of the plasma membrane. R. Tendler was always disappointed with these responses and remarked that the students were both poor scientists and deficient as “observant” Jews because they did not see the real picture. Torah-educated students should have derived an important conclusion from viewing a human cell under a microscope: The palpable sensation of encountering God as the Bore Olam, the creator of life. Just as Avraham recognized Hashem when he viewed the stars in the sky, we should also recognize that He created this world through our observation of the microscopic human cell and appreciate the divine beauty of biology. 

These reminiscences of my privileged, decades-long relationship with R. Tendler are but a small taste of a Gadol whose knowledge of Talmud, Jewish law, and medicine impacted many thousands of rabbis, physicians, students, and people around the world. Learning and writing with him was a unique and special privilege. The Jewish world will never forget how R. Tendler empowered us to value the wonderful and complex interface between science and halakha. His teachings have enabled us to better understand both realms, and strengthen our commitment to each. 

Dr. John Loike is Interim Director of Bioethics at New York Medical College and Professor of Biology at Touro College. Rabbi Tendler zt”l taught him and inspired his educational path.


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