The more you read the more you are able to think about a subject.
I wonder how Spurgeon would have done in the computer age. He had nothing but his pen. He had his books to read. He read books, which are now out of print.
How he had the ability to speak to great crowds is beyond my understanding. Of course there are many who do this very thing today. Billy Graham to name one.
I guess what I am trying to say, Spurgeon had a method that he was able to use to present and prepare a sermon. Understanding that the Holy Spirit was the guide to his thinking. Of course we believe that God via the Holy Spirit gives us direction as to preparation of sermons.
This pfd site has 216 pages of 41 sermons by Spurgeon
Charles H. Spurgeon's Personal Library
Emmett O'Donnell of spurgeongems.org announces all 3,563 C. H. Spurgeon sermons are now on his website.