According to Etymonline, living dates to the 14th century, and refers to
"the fact of dwelling in some place," from O.E. lifiende, prp. of lifan
But we hear the phrase "the living rock" used all the time. For example, in George R. R. Martin's A Storm of Swords:
Down a twisting passageway he went, narrow steps carved from the living rock, down and down.
I get that this is used in the sense of dwelling, as in the rock dwells in some place, but it still seems curious to me, even though I've accepted it every time I've encountered it in print my entire life.
Webster's 3rd New International Dictionary gives the expression "living rock" to mean
remaining uncut or unquarried: NATIVE <in places the track was hewn out of the ~ rock — Geo. Journal>
That just regurgitates what we all know it to mean. But can anyone shed some light on where this was first used, or how it came to be such a standard trope?