In 1978, Cyrus H. Gordon defined and outlined a previously unknown literary technique he called Janus parallelism. The Roman god Janus had two faces, one looking forward and one looking back, hence the name. A Janus parallelism is where the middle stich in poetry is ambiguous in that it is applicable to both the preceding and following stich. In other words there is a double parallel in the poem.
One example is from the Book of Job 1:20 which says:
1) he rends his garment;
2) he shears his head;
3) he falls to the ground; and
4) he prostrates himself
The first two actions are those of mourning and the final election is that of praising. The third action is deliberately ambiguous as it could relate to both.
Examples of Janus parallelisms have also been found in the Book of Mormon by Paul Hoskisson such as 1 Nephi 18:16, 2 Nephi 4:20 and 1 Nephi 10:13 which says:
that we should be led with one accord into the land of promise,
unto the fulfilling of the word of the Lord,
that we should be scattered upon all the face of the earth.
In this instance, the “fulfilling of the word” relates to both being led to a land of promise and being scattered upon the face of the earth.
Where would Joseph Smith have learned to do this?