lo and behold

The lo in the expression probably originated from the shortening of the word look, commonly seen in Middle English texts. Its presence in literature can be traced to at least as early as the 18th century. The literal meaning of the expression is "look and see", and it is always used as if in the imperative.

lo and behold

1. Used to express surprise.
   • 1766, "Miss N", Select letters Between the Late Duchess of Somerset, Lady Luxborough, Mr Whistler, ... and Others, Thomas Hull (editor)

     Here was I sat down, full of Love and Respect to write my dearest Friends a dutiful and loving letter, when lo, and behold! I was made happy by the receipt of yours.

   • 1995, Robin Hobb, Assassin's Apprentice : The Farseer Trilogy Book 1, Del Rey Mass Market Edition, p. 117.

     And when Regal and I rode down to get it, lo and behold, it's from Patience, to tell us Chivalry's dead.