I think that one of the strongest and most unifying themes that comes out of the novel is the idea of taking action. Life is defined as the reality of needing to take action and not be inhibited by waiting or paralysis of action. This is a unified theme because it is presented throughout the narrative in different forms. Chris is an example of this. When he tells Edie "to wait," it is a telling moment as Edie begins to recognize that her life is defined in terms of waiting and taking action. As her own epiphany enhances her characterization, Edie speaks to this:
If there were women all through life waiting, and women busy and not waiting, I knew which I had to be.
I think that this notion of not waiting for life, but actually taking action and living it is a unifying theme in the story because it speaks to a world without being inhibited by class settings and by other social prejudices as well as personal inhibitions. It speaks to the idea of needing to take action in order to live life and in this, there is a powerful element present in the narrative and a unifying theme intrinsic to it.