1 Nephi 1:6

6 And it came to pass as he prayed unto the Lord, there came a apillar of fire and dwelt upon a rock before him; and he saw and heard much; and because of the things which he saw and heard he did bquake and tremble exceedingly.

It was Lehi’s actions that brought about the response from the Lord.
What is a pillar of fire? The word dwelt seems to imply something more than rested, landed, was on, or describing its location. To dwell has implies elements of living, of existing and of state; as in to dwell in a stat of joy. Could this be one of the heavenly means by which God can communicate to man scenes of history and scenes in the future? Is this like a holographic projection? It does state that the rock it dwelt on was “before him” (in front of him). This definitely appears to be different than a vision, where the understanding of the receiver’s mind is opened to receive the information directly. Maybe this is a means used when the receiver is not yet prepared for the information by dream or vision.
We are led to understand that in vision, the length of time is not a fixed requirement to communicate a volume of information. Is the same true for this means or was this more like watching a movie? We are told that he saw and heard much. If this was a communication received by the physical senses (eyes and ears), maybe it was watched and listened to.
However it was received, it caused Lehi to quake and tremble a great deal. Reading this in the past I have always thought that it was the content of what he saw and heard that made him react this way. There may also have been a physical reaction to such an unusual occurrence. A pillar of fire on a rock would certainly unsettle me. Second and even more profound; the pillar must have required the power of the Holy Ghost to come upon Lehi to operate. This power (as explained by Joseph Smith) takes some getting used to. It must be physically draining and that probably added to Lehi’s overall condition. He may have seen his own part in crying repentance to the people. That would really be frightening.