This gesture accompanies the Birkat Kohanim, or Priestly Blessing, an ancient Jewish custom. The Blessing is administered by members of the Kohanim, or priestly class, usually on holidays. The hands are spread into two “V” shapes, in the form of the Hebrew letter Shin () and symbolizes the light of the Shekhina, or Presence of God.
The blessing itself is taken directly from that given in the Book of Numbers:
“The Lord bless and keep you.
The Lord let His face shine upon you, and be gracious to you.
The Lord look upon you kindly and give you peace.”
The resemblance of the gesture to the “Live long and prosper” salute of the Star Trek character Spock is not coincidental. Actor Leonard Nimoy has remarked on several occasions that the gesture was a nod to his Jewish heritage.