Reviews in Brief

Reviews in Brief – Winter 2023


Yedias HaTorah Step by Step: A Practical Guide to Retaining Your Learning
By Rabbi Dovid Schoonmaker 
Shapell’s/Feldheim Publishers
New York, 2022 
109 pages

Some people are blessed with exceptional memories. The rest of us struggle to remember what we ate for breakfast, much less what we learned six months ago. However, to some degree, memory is like a muscle that can be strengthened through training and regular exercise. In this short but powerful book, Rabbi Dovid Schoonmaker, rosh yeshivah of Darche Noam (Shapell’s) in Jerusalem, offers clear and specific advice on how to improve your ability to remember the Torah you learn. While the book revolves around the study of Gemara, it can be applied to any area of Torah.

Rabbi Schoonmaker’s technique involves four steps, which I am somewhat adapting for purposes of this review. First, learn with clarity so you understand the material you want to remember. Then, write summaries of the material. Third, create simanim—acronyms or other clever wordplays to link concepts. And finally, review your summaries and simanim on a regular basis.

Zichru, for example, is a program that follows this method through the Daf Yomi cycle. On every daf of Gemara, Zichru provides a summary of three points to remember. Then it presents a story and a picture connecting the four pieces of information you want to remember (the daf number and the three points). Participants in the program review the pictures and stories many times across weeks and months, thereby accumulating a memory of hundreds of pages of Gemara.

In this important book, Rabbi Schoonmaker teaches readers how to adapt this technique to their own personal schedules and selected Torah texts. Along the way, he offers additional important advice, such as choosing to learn the areas you naturally remember best, and teaching something to help you remember it better. Most importantly, unless you have an exceptional memory, you must learn with intentionality. If you take the basic steps in the book to consider how you can improve your memory, and you follow through and continue to review the material, you can vastly expand your Torah knowledge. 


The Halachic Haircutting Handbook: A Breakthrough Exposure of an Obscure Mitzvah (Second Edition)
By Rabbi Chaim and Binyamin Jachter
Kol Torah, 2023
107 pages

Over the past few years, a plethora of books and articles—most of them sent to my house without my permission by an enthusiastic opponent of shaving—have been published that argue that halachah forbids men from shaving their beards. Kabbalah in general, and Chassidic thought in particular, emphasize the spiritual importance of a man’s beard. For this mystical reason, many men never trim their facial hair at all. However, the current argument claims that it is forbidden to shave for halachic, not mystical, reasons.

This is puzzling to many because common practice in the yeshivah community for at least a century is that beards are for married men. The yeshivah in Slabodka required single men to remove their facial hair unless they came from Chassidic families. Even after the advent of the electric shaver, this common practice continued for decades. Most yeshivot now allow for more personal autonomy on such issues, but the clean shaven look is still standard.

The current would-be debate revolves around the permissibility of electric shavers. In a short but powerful book, Rabbi Chaim and Binyamin Jachter review the debate among posekim whether use of an electric shaver constitutes a violation of the prohibition to shave with a razor (Vayikra 19:27). One aspect of the debate is whether the Talmud allows shaving with scissors. Another aspect is which, if any, electric shavers operate like scissors. Those who permit shaving with scissors would allow an electric shaver that functions in a scissor-like manner. In a surprising breakthrough, Rabbi Jachter and Binyamin Jachter spoke with engineers and examined videos of shaver tests to clarify exactly how they function. Their unequivocal conclusion is that facial skin does not provide enough resistance for an electric shaver to cut against. Rather, all electric shavers function like scissors.

After showing their evidence to a number of leading rabbis and posekim, the unanimous conclusion is that these electric shavers are permissible. The authors conclude that almost all electric shavers are permissible and add that while they use the word “almost,” they are not aware of any electric shaver that is forbidden. This does not mean that men must shave their beards or that there is no room to choose to be strict regarding the opinion that shaving with a scissor is forbidden. However, the authors emphatically demonstrate that there is ample room to permit using any electric shaver currently on the market.


DNA in Halakhah  
By Rabbi J. David Bleich 
Ktav Publishing 
New York, 2021
296 pages

It is rare to find a new phenomenon about which halachah has nothing to say. Some would say that no such phenomenon exists. However, it requires great skill and creativity to find the right halachic category from the agrarian lives of the Talmudic rabbis and apply it to new inventions. As technology develops in leaps and bounds, scholars put forth initial, tentative analyses based on classical sources that are then subject to debate. Often, the dust eventually settles, and a consensus arises that serves as a baseline approach for future generations. This happened with the printing press and continued throughout the generations. The rapidly developing technology of our times is no different.

For over half a century, in his plentiful articles and books, Rabbi J. David Bleich has been at the forefront of reviewing and critiquing the initial scholarly attempts to halachically evaluate new inventions and phenomena. With legendary erudition, Rabbi Bleich breaks down new questions into component parts and categorizes the different approaches found in contemporary halachic literature. Along the way, he critiques the different views and offers support where he believes appropriate. His important book, DNA in Halakhah, follows that familiar approach.

DNA testing seems like a scientifically decisive proof, and therefore, it should presumably be embraced by religious decisors and courts. In many ways, DNA should be treated like fingerprint and blood-type evidence. However, as Rabbi Bleich shows through his survey of the science and methodology of DNA testing, it really only constitutes circumstantial evidence of a high probability. There likely is no one with the same DNA as you, but that is not definite, because biological anomalies occur, even if only rarely. That is aside from potential laboratory errors. Is a DNA match a rov (majority), an umdena (presumption), an anan sahadei (testimony) or something else? What happens when you have evidence or presumptions pointing in the other direction?

These are among the most difficult topics in halachah. The complexity of each concept multiplies dizzyingly, as different analyses are offered in the halachic literature throughout the ages. Rabbi Bleich takes readers through the discussions in classical literature, as well as the decisions of contemporary decisors and religious courts, as he explores the evidentiary power of DNA in cases relating to paternity, agunot, mamzerut, kohen genes and much more. With his characteristic clarity and organization, Rabbi Bleich offers readers a window into the cutting edge of halachic decision-making.  


Rabbi Gil Student writes frequently on Jewish issues and runs He is a member of the Jewish Action Editorial Board.

This article was featured in the Winter 2023 issue of Jewish Action.
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