People who know the book "1984" only:

What page is the quote "“For, after all, how do we know that two and two make four? Or that the force of gravity works? Or that the past is unchangeable? If both the past and the external world exist only in the mind, and if the mind itself is controllable – what then?” on? I am doing an essay on totalitarian governments and need the answer:
ASAP.

Offering 70 points.