"Kabbalah teaches that every Hebrew letter, word, number, even the accent on words of the Hebrew Bible contains a hidden sense; and it teaches the methods of interpretation for ascertaining these meanings." - sourceThree of these methods are Notaricon, Gematria, and Temurah. While primarily used as a means to interpret the scriptures, they can be used elsewhere, so an overview of the methods can be helpful to the genealogist with Jewish ancestry. (An overview is pretty much all I know and can provide; I don't have deep knowledge.)
Notaricon – A method of using the initial and/or final letters in a group of words to form words/phrases.
Several months ago I wrote about my great-great grandfather, Moshe Leyb "the king". At least one of his daughters referred to him by that epithet, probably as a Hebrew joke, based on the initials of his name. This of course is a usage of Notaricon. Similarly, Moshe Leyb was honored with several grandchildren, one named Melvin Lester, another Monroe Leslie, and a third Morris Louis. Without knowing the importance of initials in Kabbalistic thought, this might appear to be a coincidence of names instead of grandchildren being named after their deceased grandfather.
BTW: Leyb is the Yiddish word for Lion. Leyb was one of several new animal names which became popular in the European Jewish community in the 18th century. Prior to that animal names were common, but were limited to those that had appeared in the bible.
Both Yiddish and Hebrew variants are used, and sometimes interchangeable. One of my ancestors on some documents was Zev Perlik and others Wolf Perlik. (Since many English words are Germanic in root, and since Yiddish has Germanic roots, sometimes Yiddish and English words are the same.)
Many immigrant Jews Americanized their names, and often they did this by finding a common American name that began with the same initial letter(s). Until recent research, I thought Wolf Perlik's name was "William" as that is how it was recorded in our family documents. William, of course, shares the first two consonants with Wolf. Wolf didn't immigrate, but some of his children 'changed' his name to 'William' in the oral history. Similarly, another ancestor's Hebrew name was Zvi, or 'deer.' The Yiddish variant is 'Hirsch', and a common Americanization is, "Harry."
Without knowing the animal names, and the process of Notaricon, one might be very confused how the name 'Harry' was derived from 'Zvi'. This tradition of using the initial letter or letters to change names can be useful for parents if an ancestor had a name that is uncommon today.
Gematria – A method of assigning numerical values to letters, calculating the numerical value of words/phrases, and associating them with other words/phrases of matching value.
Perhaps the best known example of Gematria is with the Hebrew word, 'chai,' meaning 'life.' Formed with the Hebrew letters Chet (8) and Yod (10), the numerical value is 18. Many Jews will give charitable donations in multiples of $18 to symbolize 'life'.
I don't know of any examples of names of children/grandchildren that were gematrical equivalents of ancestral names. Though I haven't computed the numerical value for all of my ancestors Hebrew names, either, and I'd have to perform the math to notice.
However, there is a genealogical connection in that you will find something similar to gematria in the Hebrew writing on gravestones. The dates on the Hebrew calendar are converted to letters.
Temurah – Exchanging letters in words to create new ones. There are three primary types of Temurah. (I'll use the Roman alphabet to illustrate)
1) (Atbash) A exchanged with Z, B exchanged with Y, C exchanged with X...
2) (Avgad) A becomes B, B becomes C, C becomes D...Z becomes A.
3) (Albam) A exchanged with N, B exchanged with O, C exchanged with P…M exchanged with Z.
Once again, I don't know of any examples in my family tree where names were created using one of these methods, and I haven't heard of it happening in other families. However, there is one example from literature.
Some creative readers suggested that Arthur C Clarke came up with the name for his misbehaving computer in the novel, 2001, through a reverse-Avgad technique -- HAL being derived from IBM. Clarke has denied this, insisting it was a coincidence, and that the name is actually a Shakespearean reference to Henry V, referred to as Prince Hal in the drama, Henry IV. Clarke probably expects readers to believe that since he is British, he is more likely to make a Shakespearean reference than a reference to an American computer company. Yeah, right.
I've not been trained in any of these methods specifically. I knew about gematria growing up solely through the importance of Chai and the number 18. Some examples appear in the book/film The Chosen by Chaim Potok, which I remember reading in high school. I read the book, The Bible Code a few years ago which goes into some more detail.
I've been fascinated with numerology for a long time. (as several posts on my personal blog indicate). When recently a nephew was born at 6:37 pm, I 'rounded down' in 'military time' to 18:36:54. I'll never forget the time he was born. Interestingly, I recently discovered in my maternal grandfather's addressbook that next to my birthday was written the time I was born. (12:05 pm) I have no idea why it interested him, but the time is not written next to any other birthday. Jokes have been made over the years that I was 'born just in time for lunch".