These two verses are Mormon’s introduction to what happened after Moroni received Pahoran’s letter. It represents an interesting aspect of Mormon’s style. We will often see Mormon presenting emotions in opposite pairs. In this case, we have the “exceedingly great joy” followed immediately by “also did mourn exceedingly.” The things that caused joy were certainly present, as were the reasons for mourning. It is the presentation of the two emotions as opposing pairs that perhaps underscores one of the ways in which Mormon viewed the world. For Mormon, it was not infrequent that he would write of things in terms of this type of opposition. There was good and evil, and while Mormon might have realistically seen the shades of gray in between, we more often see him describe the world in the stronger opposites.