Nephi records that the Lord commanded his father, "even in a dream" (1 Nephi 2:2). According to Brant Gardner, the prophetic mode of communication by the Lord to Lehi seems to have been through the medium of dreams. Nephi even comments that his father had "written many things which he saw in visions and in dreams " but that he (Nephi) "shall not make a full account [of them]" (1 Nephi 1:16). In Old Testament times, dreams were an acceptable means of receiving communication from God. It is interesting that one of the most famous dreamers of the Old Testament was Joseph of Egypt (see Genesis 37:5-10). Joseph not only received dreams which indicated that he would eventually rule over his brethren, but also served as the dream interpreter for Pharaoh.
Dreams are full of images. These images can be symbolic, sometimes heavily so as with the Apocalypse of John. The difficulty in interpreting the symbolic dreams is probably one of the reasons why Lehi's family will not give him full support during the times of crisis. Not only will Laman and Lemuel deride their father as a "visionary man" (1 Nephi 2:11) but even his wife Sariah will emphasize her concerns by referring to him as such (see 1 Nephi 5:2). Even Nephi will apparently struggle to understand that which his father saw (1 Nephi 2:16; 11:1). It might be for this reason that Nephi's accounts of his father's dreams, with the exception of the Tree-of-Life dream, are typically quite abbreviated, and relegated to a restatement of the purpose rather than the precise content of the dream. [Brant Gardner, "Brant Gardner's Page, "[http://www.highfiber.com/~nahualli/LDStopics/1] Nephi/1 Nephi2.htm, pp. 1-3]