We are commanded to keep Pesach for 7 days in the Torah. I'm wondering if any reasons have been developed by anyone throughout Jewish history for why 7 days.
In other words, what is the significance of 7 in the context of how long Pesach (and what the holiday stands for) should be celebrated?
Additionally, for the future, how would I answer a specific/obscure question like this on my own. Would I need to brute force it by doing a whole "review of literature"? Which seforim are likely to have these kinds ideas in them?