Last year, BYU Studies announced that they were placing the Archive of Restoration Culture online. This database consists of statements from contemporaneous sources about doctrines that are now viewed as distinctly Mormon. If you’ve ever wondered, “Was anyone else discussing an idea like three degrees of glory, around the time Joseph Smith wrote?” — this is where you find your answer.
The database is the product of dozens of graduate student researchers, working under the direction of Richard Bushman. I’ve only skimmed it to date, and I’ve already found some remarkable materials. If you haven’t yet looked at the database, you may want to consider doing so. It’s available online (in a 7 megabyte pdf file), at http://byustudies.byu.edu/Resources/arc.aspx .