History or the future?
...is what the science of history *reveals*, I would say.
That depends on how it's written.
History is written, "the science of history" is something larger. If that science would be in the business of hiding terrors to come, oh dear...
The quote is from Roth's alternate history book The Plot Against America. His point is that historians (typically) make developments seem inevitable in retrospect, but to a certain extent that falsifies the experience of living through the events, and perhaps makes the contingent seem necessary. Kierkegaard said it more concisely: Life can only be understood backwards, but it must be lived forwards.
I'm with Kierkegaard here — we are oarsmen that can only look backwards. The suggestion of inevitability is indeed a problem for historians. Over here there has been a book that presented history in the form of newspaper front pages, which was a refreshing approach. Harry Mulisch has suggested that history lessons in school should not start with the Ancient Greeks but with yesterday's newspaper.