How does FeedJack fetches historical feeds

I am building a news aggregation website and I am looking for a way to fetch old feeds(of any particular website ) into the system. During this course, I stumbled on to Feedjack. It is said that it handles what I needed. So I started diving into the source code. (I dont want to plugit in my django project directly.) All I see is this line:

self.fpf = parse_feed(self.feed.feed开发者_JAVA百科_url, agent=USER_AGENT, etag=self.feed.etag) # in bin/feedjack_update.py

I am not sure how this handles historical feed parsing. May I know what I am missing. One more question I have is, let alone feedjack, how can I access historical feeds of any website?

Historical feeds aren't available from websites. Unfortunately, the only way to "access" it is to store it yourself in a database. For common feeds, you may be able to get it from another aggregator. Otherwise, you build up the history starting from when the feed is first added.

The only option I can see is using Google Reader. There is a blogpost about constructing feed history of any feed. I dont want to stick on service for just getting the historical feeds. Anyway, if there isn't any better option, I would go for that.