The Lord explains the problem of light to the brother of Jared. The Lord does not provide the solution, but only the parameters of the problem. As with the rest of his children, the Lord wants us to learn to think and work out problems on our own. Of course he wants us to come to him for advice, but not in such a way that we abdicate our agency and God-given reason. The Lord makes certain that the brother of Jared understands the outline of the problem of light.
The first problem of light is that they cannot have windows. The reason given is that they would be “dashed in pieces.” This phrase has caused several problems for the historicity of the Book of Mormon because it seems to suggest that the windows would have been glass. There are multiple problems with the assumption of glass windows. Even if we accept that there was some glass technology at this time as Nibley suggests (Hugh Nibley. Lehi in the Desert and the World of the Jaredites. Bookcraft, 1952, p. 213-4), the ability to make glass into small beads is a long way form sheets of glass mounted in frames to be windows.
The explanation of the windows dashed in pieces must refer to something else, and the most likely probability is shuttered holes. Such a “window” does not require glass, but simply some form of covering. It is therefore possible that the reference is to some form of wooden shuttering, something that would be much more likely in the ancient world than glass windows.
The windows cannot provide light when they are under water, even though they would have been effective above water. The reason is that they could be broken, and the water would come it. This suggests that the door of the barges also had to have some reinforcement or sealing to prevent a similar problem.
The second issue was the inability to carry fire. Even though there is an inherent problem of having fire in a wooden boat, the reason does not appear to be given because of the fire hazard. The brother of Jared is told that they cannot have fire because “ye shall go as a whale in the midst of the sea.” When the barges are underwater, then the fire becomes a problem. Of course the reason is that fire consumes oxygen, and a fire while they were submerged would be consuming precious oxygen right at the time when that oxygen was most in need.
Textual: There is no chapter break at this point in the 1830 edition.