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Question: Did Joseph mention a "pillar of fire" or a "pillar of light" in his 1832 account of the First Vision?
Question: Why did Joseph mention a "pillar of light" in his 1832 account, but a "pillar of fire" in his 1835 account of the First Vision?
Joseph Smith's 1832 account mentions a "pillar of fire," which he then crossed out to replace with "a pillar of light"
Joseph did indeed dictate "pillar of fire" in his 1832 journal account. He then crossed out the word "fire" and wrote "light." Therefore Joseph wrote both "pillar of fire" and "pillar of light."
Joseph was not certain of how to describe the light that he saw, characterizing it as both "fire" and "light." Orson Pratt, in his 1840 pamphlet "A[n] Interesting Account of Several Remarkable Visions," wrote of a "very bright and glorious light" which descended, yet he gave it the characteristics of "fire" when he noted that Joseph "expected to have seen the leaves and boughs of the trees consumed, as soon as the light came in contact with them."
[Joseph], at length, saw a very bright and glorious light in the heavens above; which, at first, seemed to be at a considerable distance. He continued praying, while the light appeared to be gradually descending towards him; and, as it drew nearer, it increased in brightness, and magnitude, so that, by the time that it reached the tops of the trees, the whole wilderness, for some distance around, was illuminated in a most glorious and brilliant manner. He expected to have seen the leaves and boughs of the trees consumed, as soon as the light came in contact with them; but, perceiving that it did not produce that effect, he was encouraged with the hopes of being able to endure its presence. It continued descending, slowly, until it rested upon the earth, and he was enveloped in the midst of it. When it first came upon him, it produced a peculiar sensation throughout his whole system. 
Some critics of the Church wish to portray "pillar of light" or "pillar of fire" as a discrepancy between accounts
The is no discrepancy here: Joseph wrote "pillar of fire" in his 1832 account, and then crossed out the word "fire" and replaced it with "light." In his 9 November 1835 account, he states "a pillar of fire." In the canonized 1838 account, he describes it as a "pillar of light." The fact that in 1832 Joseph ultimately decided to write "pillar of light" does not negate the fact that Joseph originally wrote the words "pillar of fire" in his record. Some critics has attempted to show a discrepancy between the 1832 account and later accounts by pointing out that Joseph wrote "pillar of light." For example, the following critical graphic incorrectly represents the 1832 account.
- "Appendix: Orson Pratt, A[n Interesting Account of Several Remarkable Visions, 1840,"] The Joseph Smith Papers.