" Lo in this and its other meaning, which is more akin to O!, has been in use since the first Millennium and appears in the epic poem Beowulf."
It also offers the first written record of the full phrse, "lo and behold" in an 1808 letter in theCorrespondence 1787–1870, of Queen Victoria's lady of the bedchamber - Lady Sarah Spencer Lyttelton:
"Hartington... had just told us how hard he had worked all the morning... when, lo and behold! M. Deshayes himself appeared."