What is this "now"? Is it "now that" or "because"? Or what else?

ex)There is a strong view that holds that success is a myth, and ambition therefore a sham. Does this mean that success does not really exist? That achievement is at bottom empty? That the efforts of men and women are of no significance alongside the force movements and events? Now not all success, obviously, is worth esteeming, nor all ambition worth cultivating.....