A friend wants to know the origin and significance of the abbreviation yud yud, used for God's name in some siddurim (prayer books), as opposed to yud kay vav kay, that is also used.
I told him yud yud is unpronounceable, cannot easily be mistaken for any actual word and, perhaps more importantly to scribes and typesetters, is smaller, being made of fewer letters than yud kay vav kay. And yud is itself the smallest letter physically in the entire alphabet and perhaps the easiest to write.
He rejects this explanation noting there are old sources* that use yud yud. His reasoning is that, if sources from the pre-printing press era used the abbreviation, the reasons I gave cannot be primary.
It occurs to me that the sources he cites are all in print, meaning at some point a printer had to take a manuscript copy, typeset it and run it through a press, so the pre-printing press era sources cited are not actually pre-printing press era unless a manuscript, rather than a printed version, is cited.
Further, it is not clear to me why the reasons I gave are invalidated if the work is handwritten.
Do any of you know the origin of the yud yud abbreviation? If so, or if you have any thoughts on this, please leave them in the comments section below. Thank you.
* He cites from Jastrow, page 576: "Targ. Ps. I, 2 (ed. Lag. 'YHVH'); a. fr. - Y. Sanh. X, 28a top; a. fr. Iinterch. in eds. with 'H')."