I offer this in fond memory of Leonard Nimoy, who played one of childhood heroes, Mr. Spock from Star Trek. (So as not to date myself, I’ll hasten to add that it was in syndication).

I have read that when Leonard Nimoy came up with this gesture for Mr. Spock’s famous “live long and prosper” Vulcan salute, he was thinking back to his childhood religion of Judaism.  This reflects the gesture of the kohanim (descendents of Aaron, the brother of Moses) when giving what is called the Aaronic blessing.  This is recorded in the pages of the Old Testament:

And the Lord spake unto Moses, saying, “Speak unto Aaron and unto his sons, saying, On this wise ye shall bless the children of Israel, saying unto them,
The LORD bless thee and keep thee:
The LORD make his face to shine upon thee, and be gracious unto thee:
The LORD lift up his countenance upon thee, and give thee peace.
And they shall put my name upon the children of Israel, and I will bless them.
(Numbers 6:22-27)

Leonard Nimoy discussed this in a 2000 interview with the Baltimore Sun (online here):

“It was my addition to the character, and it came from an experience I had as a child with my parents. In the blessing, the Kohanim (a high priest of a Hebrew tribe) makes the gesture with both hands, and it struck me as a very magical and mystical moment. I taught myself how to do it without even knowing what it meant, and later I inserted it into “Star Trek.” There was a scene in one episode that needed something. People were seeing other members of the Vulcan race for the first time, and I thought it called for a special gesture.”

This blessing (without the gesture) has carried into Christianity as well, and is often given at the end of a church service, as a benediction.  As you might expect, this blessing has inspired musicians and composers as well.  I leave you with lovely setting of the benediction, which I have found.  The composer was Christian Peter Lutkin (1858–1931), a respected choir director and organist who became the first dean of the School of Music at Northwestern University in suburban Chicago.