45 Ye are swift to do iniquity but slow to remember the Lord your God. Ye have seen an angel, and he spake unto you; yea, ye have heard his voice from time to time; and he hath spoken unto you in a still small voice, but ye were past feeling, that ye could not feel his words; wherefore, he has spoken unto you like unto the voice of thunder, which did cause the earth to shake as if it were to divide asunder.
(1 Nephi 17:45)
55 And now, they said: We know of a surety that the Lord is with thee, for we know that it is the power of the Lord that has shaken us. And they fell down before me, and were about to worship me, but I would not suffer them, saying: I am thy brother, yea, even thy younger brother; wherefore, worship the Lord thy God, and honor thy father and thy mother, that thy days may be long in the land which the Lord thy God shall give thee.
(1 Nephi 17:55)
Joseph Fielding Smith said:
The Spirit of God speaking to the spirit of man has power to impart truth with greater effect and understanding than the truth can be imparted by personal contact even with heavenly beings. Through the Holy Ghost the truth is woven into the very fibre and sinews of the body so that it cannot be forgotten (Teachings of the Presidents of the Church: Joseph Fielding Smith, Chapter 14: The Gift of the Holy Ghost).
Why is that? I think it is a question of agency. The Holy Ghost will only speak to us when we invite Him into our hearts. On the other hand, we may hear the words of another person, or even an angel, without wanting to hear them. When we learn from the Holy Ghost, we are an active part of the process, and the truth we learn becomes part of us. But when we hear other people, we may be passive learners, and the truths they teach may never sink into our hearts.
In the first passage above, Nephi reminds his brothers that they have seen and heard an angel. But, he tells them, “ye could not feel his words” (1 Nephi 17:45). In the second passage, the brothers acknowledge that Nephi has the power of God: “We know of a surety that the Lord is with thee, for we know that it is the power of the Lord that has shaken us” (1 Nephi 17:55). This statement of testimony seems like a significant turning point in their lives. However, it produced no lasting impact on their behavior. Why not? Because Nephi had made the effort to receive the Holy Ghost and to internalize what he had learned. Laman and Lemuel were passive learners – seeing an angel and recognizing the power of God in their brother but not actively seeking to receive the Spirit of the Lord in their own hearts.
As President Thomas S. Monson counseled us in the most recent general conference:
If you do not have a firm testimony of these things, do that which is necessary to obtain one. It is essential for you to have your own testimony in these difficult times, for the testimonies of others will carry you only so far. However, once obtained, a testimony needs to be kept vital and alive through continued obedience to the commandments of God and through daily prayer and scripture study (“The Power of the Book of Mormon,” General Conference, April 2017).
Today, I will invite the Holy Ghost into my heart. I will be an active learner of the gospel and will strive to internalize the truths I am taught by opening my heart to the Spirit of the Lord.