LotR -- Book 1 - Chapter 02 - The Shadow of the Past

[HerenIstarion]

Mark, I would be glad to be of service

Here is the quote:

Letter #192 to Amy Ronald, 27 July 1956

Frodo deserved all honour because he spent every drop of his power of will and body, and that was just sufficient to bring him to the destined point, and no further. Few others, possibly no others of his time, would have got so far. The Other Power then took over: the Writer of the Story (by which I do not mean myself), 'that one ever-present Person who is never absent and never named'

cheers