This text was prepared by William Gross:
It was customary for Mohalim (circumcisers) to possess circumcision books which contained the laws and prayers relating to circumcision as well as directions for the mohel regarding the proper procedure for performing the ceremony. These books were intended to be brought to the circumcision ceremony and were consequently small in size to as to be easily portable. Such books are found in manuscript form, especially in the 18th century as a part of the renaissance of small illustrated prayer manuscripts. But printed books were cheaper and more accesable to the average mohel.
This famous compilation of circumcision laws and prayers, Sod ha-Shem (The Mystery of God), was written by R. David ben Aryeh Leib Lida. It also includes the kabbalistic commentary Sharvit ha-Zahav. Up to the middle of the 19th century, Sod ha-Shem was reprinted 14 times in various cities. There are six edition in the Gross Family Collection.
The present volume has additional pages at the end recording close to 100 circumcision events effected by the mohel who owned the book.