Research on Ancient Phylacteries Reveals Evolution in Jewish Law

A groundbreaking study has revealed that the phylacteries, or tefillin, used by Jews over 2,000 years ago in the Holy Land were likely the natural color of their leather, not dyed black as mandated by contemporary Jewish law. This discovery was detailed in a study published in the peer-reviewed journal PLOS ONE.

“This is a very important discovery,” stated Prof. Yonatan Adler of Ariel University, who led the research. “This is the first time that tefillin have been scientifically examined to determine their color.”

Phylacteries are small leather boxes containing scriptural verses, affixed to the heads and upper arms of observant Jewish men (and sometimes women) during morning prayers. Today's tefillin must be black, adhering to detailed halachic (Jewish Law) requirements.

The study, a collaboration between Israeli and British researchers, analyzed 2,000-year-old tefillin cases discovered in the Qumran caves, famous for the Dead Sea Scrolls. The findings showed no evidence of dye, indicating that the ancient tefillin retained their natural leather color.

The Gemara, a foundational Jewish legal text from around 500 CE, mentions that tefillin straps should be black, but debates whether the boxes must also be black. The study's results suggest that dyeing the tefillin black might not have been widespread until after this rabbinic ruling.

Using advanced techniques such as multispectral imaging, Raman spectroscopy, ATR-FTIR spectroscopy, and SEM/EDX, the researchers determined that the dark appearance of some ancient tefillin was due to natural aging rather than intentional dyeing.

“In the dark fragments we examined, the color appears to be the result of natural leather aging rather than intentional dyeing… In the past, we have found that some of the Dead Sea Scrolls have also undergone a similar process, which unfortunately has caused the parchment to darken,” explained Dr. Yonah Maor of the Israel Antiquities Authority’s analytical laboratory.

The ancient tefillin, found in 1949 and subsequent years near Qumran, date back to the end of the Second Temple period, around 2,000 years ago. Their preservation is largely due to the desert climate. These artifacts are now housed in the IAA’s Dead Sea Scrolls Unit in Jerusalem, maintained in conditions similar to their original environment.

Prof. Adler noted that the practice of dyeing tefillin black likely emerged as a later tradition, not in place during the Second Temple period. “It is likely that in the beginning, there was no halachic significance to the color of tefillin,” he said. “Only at a later period did the rabbis rule that tefillin should be colored black.”

Even after black tefillin became the standard, rabbinic authorities continued to debate whether this requirement was absolute or simply preferred for aesthetic reasons. Adler concluded, “It is commonly thought that Jewish law is static and does not develop. Our ongoing research on ancient tefillin shows that the exact opposite is true; Jewish law has always been dynamic. In my view, it is this vibrancy that makes halachah so beautiful.”

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