Studying history is useful both for learning what not to do and for learning what to do. This book definitely focuses on the latter by examining various revival experiences. The beauty of doing so is that you see that the times in which revivals happened aren't much different than what we're living in today, and you realize that what has happened before can happen again, anywhere in the world including right here in the USA.
While there are lots of takeaways from this book what stood out most to me is that revivals are costly to those at the forefront of them. And so the question looms -- are we really willing to pay the cost revival demands? Are we willing to spend extravagant amounts of time in God's presence, setting aside any competing agendas? Are we willing to be broken? Are we willing to be inconvenienced and pulled out of our comfort zone? The book is very clear -- there is no set formula for revival. You can't do a+b+c and get revival x. But you can seek the heart of God continually with great passion, and trust that your cries will be heard.