The Joseph Smith Papers: The Manuscript Revelation Book provides insight into the process of revelation

Excerpts of the July 2009 Ensign article The Joseph Smith Papers: The Manuscript Revelation Book by Elder Marlin K. Jensen regarding the dynamic process of revelation.
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The volumes in the series titled "Revelations and Translations" will reproduce the earliest manuscripts of Joseph Smith's written revelations and translations, together with the official editions of these documents as they were published during his lifetime.

Revelation Book 2 had not been readily accessible until the Church published images of the original manuscripts. Also, only in recent years have scholars begun to assess the value of Revelation Book 1, which had been in the possession of the First Presidency.

One of Joseph Smith's tasks in reviewing the manuscripts prior to their publication was to "correct those errors or mistakes which he may discover by the Holy Spirit." Occasionally, later revelations would supersede or update previously received revelations, necessitating the editing of documents to alter previous versions.

In some instances, when a new revelation changed or updated what had previously been received, the Prophet edited the earlier written revelation to reflect the new understanding. Thus, as his doctrinal knowledge clarified and expanded, so did the recorded revelations. They were characterized by the changing nature of his understanding of the sacred subject matter. The Prophet did not believe that revelations, once recorded, could not be changed by further revelation.

Read the entire article here.