The original Book of Mormon text for this passage contains a sentence fragment:
for had not the Lord been merciful to shew unto me concerning them … for he surely did shew unto prophets of old all things concerning them
In his editing for the 1837 edition, Joseph Smith attempted to eliminate this sentence fragment. He first crossed out the last for and started to write something slightly above the line, which is not fully legible. It could be the pronoun I (presumably, a first attempt at writing “I should have perished also”). It may also be some kind of defective ampersand. In any event, Joseph crossed the word out and higher up supralinearly inserted the main clause “I should have perished also”. But deleting the conjunction for made an awkward transition to the following independent clause (“he surely did shew unto prophets of old all things concerning them”); the 1837 edition ended up fixing the transition by inserting and as the connector. Clearly and works better than for, given that the main clause “I should have perished also” has been inserted between “even as he had prophets of old” and “he surely did shew unto prophets of old”.
Joseph Smith’s inserted main clause (“I should have perished also”) seems to be based on the language found a little later in the text, at the beginning of the next book:
Notice the initial use of the inverted had-clause as a conditional clause, which is then followed by virtually the same language as in the edited text for 1 Nephi 19:20. The idea that seeing a vision prevented someone from perishing (in this case, Lehi) is also found earlier in the text:
Thus Joseph Smith’s additional clause in 1 Nephi 19:20 seems appropriate. And one might go so far to suggest that the earliest textual source (the original manuscript) is indeed in error and that here the original text was re-revealed to Joseph. Although possible, this suggestion goes against all the other (very human) editing Joseph Smith did for the 1837 edition.
Actually, there is some evidence that the original language in 1 Nephi 19:20 represents a Hebraism rather than an accidental sentence fragment. Biblical Hebrew has examples of a conditional clause standing alone as the equivalent of a negative imperative or emphatic declarative clause (usually used for oaths). For instance, in the following passage from 2 Kings in the Hebrew Bible, I place the reading of the King James Bible alongside a literal translation of the Hebrew:
2 Kings 2:4
| king james bible | literal hebrew |
| and he said as the LORD liveth and as thy soul liveth I will not leave thee | and he said the life of YHWH and the life of thy soul if I leave thee |
One interesting example (pointed out by David Calabro, personal communication) involves the Hebrew equivalent of “had not I”, which is just like the “had not the Lord” of 1 Nephi 19:20:
Psalm 27:13
| king james bible | literal hebrew |
| I had fainted unless I had believed to see the goodness of the LORD in the land of the living | had not I believed to see in the goodness of YHWH in the land of the living |
The King James Bible supplied the main clause “I had fainted” at the beginning of this verse in order to avoid a stranded conditional clause. These three words are set in italics in order to show that they are not in the original Hebrew. Similarly, Joseph Smith (in his editing for the 1837 edition) supplied the main clause “I should have perished also” at the end of 1 Nephi 19:20.
Other examples of this Hebraism are found in the Greek of the New Testament. In the following two examples, I give the reading of the King James Bible set alongside a literal translation of the Greek:
Mark 8:12
| king james bible | literal greek |
| verily I say unto you | truly I say to you |
| there shall no sign be given | if a sign be given |
| unto this generation | to this generation |
Hebrews 3:11
| king james bible | literal greek |
| so I sware in my wrath | as I swore in my anger |
| they shall not enter into my rest | if they shall enter into my rest |
Blass and Debrunner state that this use of if-clauses “in oaths and asseverations is a strong Hebraism” that means ‘certainly not’. See number (4) under paragraph 372 on page 189 of F. Blass and A. Debrunner, A Greek Grammar of the New Testament and Other Early Christian Literature (Chicago: University of Chicago Press, 1961).
Given this pattern, we may “translate” the original text of 1 Nephi 19:20–21 as follows by replacing the conditional clause with a declarative main clause and by reversing the polarity (that is, by removing the negative not):
Under this interpretation, there is clearly no need in the critical text for the intervening “I should have perished also”.
Another example of this literal Hebraism in the original text of the Book of Mormon occurs when Alma threatens Korihor:
Joseph Smith removed this oath-like Hebraistic if-clause by changing the if-clause to a yes-no question (“will ye deny again that there is a God and also deny the Christ”), although even the question form can be interpreted as a threat. See Alma 30:39 for further discussion. And for a complete discussion of this particular Hebraism, see emphatic conditional clauses under hebraisms in volume 3.
Stan Larson has suggested that the passage in 1 Nephi 19:20–21 could be readily dealt with by treating the had-clause as a yes-no rhetorical question. A question mark could be placed at the end of the whole sentence: “for had not the Lord been merciful to shew unto me concerning them even as he had prophets of old?” (See page 49 of Stan Larson, “Early Book of Mormon Texts: Textual Changes to the Book of Mormon in 1837 and 1840”, Sunstone 1/4 [Fall 1976], 44–55.)
Usage elsewhere in the text, however, argues for treating had as the beginning of a conditional clause rather than a yes-no question. There are 12 occurrences of had-conditional clauses but none as a yes-no question:
Note also that two examples (Alma 56:19 and Helaman 15:15) begin with a connective for just like in 1 Nephi 19:20. Thus Joseph Smith’s interpretation of the had-clause as a conditional one is consistent with usage elsewhere in the text.
Summary: Despite its difficulty for English speakers, the critical text will restore the original Hebraistic conditional clause in 1 Nephi 19:20 (that is, without the added main clause “I should have perished also”); the following connective for will also be restored.