Winston's fascination with the past and objects that come from that time to me symbolises his desire to combat Big Brother and recover these lost times. Winston's attempt to reach through the propaganda and discover more of what happened in the past is in direct violation of what Big Brother is trying to achieve through preventing any other perspective entering the consciousness of his citizens than that which he wants them to hear.
In the end, Winston's desire to understand the past is an action that is taken in direct opposition to the desire of Big Brother. The government of Oceania wants to control the past because in the process of doing so, they are able to ensure that citizens have no memory other than what Big Brother tells them to remember. In being able to control the subjective of the masses, government becomes the source of all authority, able to recreate the past and create justifications for the present and the future. Winston understands this and his fascination with the past is an act of resistance against the government. It is within this light that one sees the significance of the act in that Winston seeks to actively create a level of dissent and opposition to a government that does not tolerate nor accept it.