The cavity of a rock

Twice in the Book of Mormon, someone hides in "the cavity of a rock". This is a strange expression. Why not just use the word "cave" since most caves are in a rock anyway? I will first share two different aspects of this expression and then take a closer look at the context of its use in the Book of Mormon.

According to a Jewish rabbi, a cave or cavity in ancient Hebrew would be a euphemism for frustration and a feeling of inability. The rock on the other hand symbolizes assurance and protection and is commonly associated with God. God is the rock of our salvation (Ps. 89:26, 95:1, 2 Nephi 9:45, Jacob 7:25, etc.). The cavity of a rock is therefore a place where you turn to God for assurance in your distress.  

A very different aspect is the historical Mesoamerican setting for this expression. I don't know where the Book of Mormon actually took place, I just find Mesoamerica the most likely alternative. In this article, Jerry Grover explains that many Mesoamerican beliefs are represented by caves and ceremonies related to or taking place in caves. Anthropologists and archaeologists have linked findings in Mesoamerican caves to both kingship and scribes. These are two out of several similarities between the two "cavity of a rock" stories in the Book of Mormon.

The first one is in 1 Nephi 3, where Nephi and his brothers hide from Laban's servants

And it came to pass that we fled into the wilderness, and the servants of Laban did not overtake us, and we hid ourselves in the cavity of a rock. (1 Nephi 3:27)

The other is found in Ether 13

13 And I was about to write more, but I am forbidden; but great and marvelous were the prophecies of Ether; but they esteemed him as naught, and cast him out; and he hid himself in the cavity of a rock by day, and by night he went forth viewing the things which should come upon the people.
14 And as he dwelt in the cavity of a rock he made the remainder of this record, viewing the destructions which came upon the people, by night.

Turning to God for assurance in great distress

This symbolism is certainly present in both these stories. Nephi and his brothers had been "thrust out" (v.25) from Laban's house. They had all their riches stolen from them, had still not obtained the plates and a small army was after them to kill them. Ether had been "cast out" from among the people after they had all rejected him and his prophecies. Being encompassed by rock in that cave gave them the kind of protection that God can offer (even though Laman and Lemuel probably saw it differently, but this was the record of Nephi).

Relations to kingship

In his article, Grover cites anthropologist Healey, who has been researching Mesoamerican caves

About the same time as the Guerrero caves were in use on the Pacific coast of Mexico, several monumental, carved, stone ‘‘altars’’ from Olmec sites on the Gulf Coast depict elite individuals of this precocious society in a cavelike front cavity. These altar ‘‘niche figures,’’ surrounded by maize imagery, have been interpreted as representations of Olmec site rulers seated in the mouth of a cave. David C. Grove (1973:134) theorizes that the ‘‘emergence from the cave’’ was central to Olmec kingship, the ruler’s mythical Underworld origins, and claims to divine status. (Healy 2007)

It may not be obvious what this has to do with the stories of Nephi and Ether. But as we know, Laman and Lemuel started beating Nephi and Sam and an angel appeared

And it came to pass as they smote us with a rod, behold, an angel of the Lord came and stood before them, and he spake unto them, saying: Why do ye smite your younger brother with a rod? Know ye not that the Lord hath chosen him to be a ruler over you, and this because of your iniquities? Behold ye shall go up to Jerusalem again, and the Lord will deliver Laban into your hands.

The angel uses a possible wordplay because rod (makel) and ruler (melech) are similar in Hebrew. Even though Laman and Lemuel were the older brothers, it was given to Nephi to rule over them because of his righteousness and their iniquity. Later, he became a ruler over the Nephites, who separated from his brothers.

The relation to kingship in the case of Ether might not be obvious either. But even though Ether was an outcast, he was the rightful heir of the throne. This is clear from the genealogy in Ether 1 and the narrative in Ether 11. Ether's grandfather Moron was king of the people but "wicked before the Lord". His kingdom was overthrown and he ended up in captivity. His son also spent all his days in captivity before Ether was born. 

Relations to scribal traditions

Another quote from anthropologist Healy (2007) in his Mesoamerican cave research

Scribes, a secondary tier of Maya nobility, also are potential candidates to have visited caves. They may have used cave pilgrimages as a ‘‘mechanism...to affirm their ongoing relationship with the supernatural’’ (Stone 2005:136, 144). Perhaps they visited these sacred places, as pilgrims, to acknowledge ‘‘the divine source of their craft, affirming their legitimacy and supporting their (elevated) social positions by doing so.’’ The cave texts at Naj Tunich, for example, include self-references to scribal visits, where they appear to have been trying to connect with the divine source of their offices. Landa (in Tozzer 1941:153) mentions that holy water, which likely came from a cave or cenote, was used in the purification rites for ancient Maya codices.

The authors examine several hieroglyphic texts from cave sites which, using the new translation for ‘‘cave,’’ seem to record ‘‘arrivals’’ of various visitors and refer to caves as ‘‘a pilgrimage or ritual center’’ (Vogt and Stuart 2005:160–162). Stuart’s earlier work with ancient Maya texts enabled him to decipher the Maya expression for ‘‘writing,’’ tz’ihb, and the phrase u-tz’ihb, ‘‘he writes’’ from one of the cave paintings of Naj Tunich (Stone 1995, 2005a:142). He went further to show that the subject of this clause was the name of an ancient Maya scribe, with a special title of itz’at, or ‘‘sage.’’ The hieroglyph suggests that the scribe in question, with two other protagonists, came ‘‘to see’’ Naj Tunich, which phrase might actually be a Maya metaphor for ‘‘pilgrimage’’. All this fits nicely with the themes, discussed earlier, of caves as pilgrimage sites and meeting places, sometimes used by scribes.

Although Nephi doesn't write anything in the cave, he is a scribe and on an important mission to obtain the Brass Plates. Ether spends his time in the cave making "the remainder of this record" (Ether 13:14).

Of course there is much uncertainty about the ancient Mesoamerican traditional uses of caves and the connections to the specific Book of Mormon stories are rather loose. But the connection is definitely there. In any case, we can learn from these stories that obtaining, preaching or preserving the word of God can lead to adversity and hardship. But if we come to the rock of our salvation, we can find refuge and safety, even by angelic visitations.