Winston purchases an antique paperweight from Mr. Charrington’s shop. By doing so, he is skirting illegal behavior by owning something aesthetically pleasing and without a clear use. He is also forming a connection to a world without the Party in it.
“[T]he Party member, like the proletarian, tolerates present-day conditions because he has no standards of comparison. He must be cut off from the past, just as he must be cut off from foreign countries, because it is necessary for him to believe that he is better off than his ancestors and that the average level of material comfort is constantly rising.”
This section from Goldstein’s manifesto explains why the Party’s maxim “Who controls the past controls the future” holds true. If people had a set of standards and norms to hold the Party against, Orwell implies, its authority would collapse.