Origin of the phrase "There, there"

[Exapno_Mapcase]

According to the Word Detective:

The consolation of that “there’s always next year” is the key to “There, there” as a comforting verbal gesture. Its role is to say “Look there, there’s something good amid the bad.” In fact the comforter often goes on to name the supposedly consoling thing, as in “There, there, she wasn’t your type anyway” or “There, there, it’s only money.”

“Now, now” is a similar verbal mechanism, but in this case it is derived from “now” as a prelude to a command (“Now do what I say!”). “Now, now” is a way of saying “Stop and listen” (as in “Now, now, children, quiet down!”).

Interestingly, both “There, there” and “Now, now” are fairly recent inventions, first appearing in those senses in the 19th century.