Narrative analysis: This verse continues the devastating condemnation of Laman and Lemuel, pointing out their ability to fall away, even after seeing an angel. Little does Nephi know that this situation will happen to them again, with no better effect.
Scriptural analysis: Even removed from its context, this is a powerful verse, with much to teach about the relationship of the Lord and his children. Like Laman and Lemuel, we are all likely to "have heard his voice from time to time" the voice that Nephi indicates is a "still small voice."The Lord will speak to us, but it is our responsibility to listen. To rework a common aphorism, there are none so deaf as those who will not hear.
The efforts of the Lord to speak to us must be matched by our ability to hear. When our hearts have been hardened, when we steel ourselves against the pricks of the spirit, we are unable to "feel his words." They may come, but they do not have the profound effect on the hard of heart that they do on the truly humble and receptive.
It is even likely that, as with Laman and Lemuel, the Lord shouts at us from time to time. In our own experience there might be the equivalent of the Lord speaking "like unto the voice of thunder." Laman and Lemuel's hearts had gone so far past feeling, that even the appearance of an angel could not permanently change their hearts, though it did have a temporary effect.
Mankind's ability to rationalize away the feelings of the communication of the Spirit are amazing. We are able to deny the undeniable, if we set upon doing so.