In chapter 7, Orwell explains that the Big Brother state occurred in much the same manner as the establishment of every communist dictatorship: through a revolution that promised deliverance from poverty and slavery but only brought worse poverty and enslavement while eliminating all individual freedom.
It is interesting that Orwell describes a series of political purges occurring to Oceania in the mid to late 1960s — precisely when in actual history Chinese tyrant Mao Zedong would institute the Cultural Revolution to eliminate any remaining figures from the 1949 revolution and murder millions in the process.
Orwell sums up freedom in the knowledge that two and two make four: it is his way of insisting that objective truth does exist.
