6 But behold, I shall take these plates, which contain these prophesyings and revelations, and put them with the remainder of my record, for they are choice unto me; and I know they will be choice unto my brethren.
7 And I do this for a wise purpose; for thus it whispereth me, according to the workings of the Spirit of the Lord which is in me. And now, I do not know all things; but the Lord knoweth all things which are to come; wherefore, he worketh in me to do according to his will.
The Words of Mormon were written by Mormon who abridged the Nephite records, and this was meant to serve as an explanation for why he included the small plates of Nephi that contain all of the preceding books (1 Nephi - Omni). Mormon included these books (unabridged) because they were choice to him, and he knew they would be important to those who would eventually have the book he had compiled. But more importantly, he included them "for a wise purpose" -- a purpose that wasn't entirely clear to him.
There are times when we feel prompted by the Holy Ghost to do something, and we don't know exactly why. One day the Spirit might whisper, "Call your son." We don't know why, but if we act in accordance with that direction, blessings will come. When we ignore those promptings, they can become harder to discern. As we learn to listen to them and act upon them, they can become clearer. It's like tuning a radio receiver (not digital, of course). An analog receiver requires some fine adjustments. We listen, and then adjust, until the signal is clear. With the things of the Spirit, we listen and then obey, and the voice of the Lord becomes clear.