I've been thinking about the question of circularity, and I wanted to post something, even if I don't have time right now for a full articulation of my thoughts:
I grew up as a Buddhist in a white Buddhist community (and am now a complete atheist). One thing I would often hear is that, unlike Western notions of history, Eastern religions conceive history in terms of circular processes, be it the process of karma and rebirth in Buddhism, or the cycle of three ages - each represented by a different god, The Creator god, the Sustainer god, and the Destroyer god - in some forms of so-called Hinduism. This complaint strikes me now as utterly blind to how the dominant trope of Western historiography actually functions: not only is there circularity, everything is circular. Western historiography refers back to the past repeatedly, in order to clarify the present: Obama=Lincoln or Obama=FDR, the current crash=Great Depression, 21st Century=20th century=19th century (but the 19th century≠the 18th century, at least not for us any more), Hitler=Napoleon=Ghengis Khan. Our conception of history is utterly circular; we cannot do without the circle. The claim that Western history doesn't recognize the circle simply fails to recognize the circle in Western history. What else is redemption than a restoration of an original state of peace?
A linear conception of time would be quite different. For one thing, it would recognize circles/cycles, but only in certain circumstances. The seasons, for example, are cyclical, but also linear. No two springs are the same, as any farmer can tell you, but we can expect the regularity of the cycle spring/summer/fall/winter (to varying degrees, of course, depending on our global location). Historically valid solutions may work a second time, but under varied conditions. Also, a linear notion of time has to recognize entropy. The movement of energy in the universe does not recapitulate the movement of the seasons. Up to this point, the dominant trope of historiography has been circular; although there have been figures that have argued for a more linear history, Marx among them (periodization is a theory that implies no reversal), the dominant trope is a circular one.