Eventually Mormon will reach the end of past history and then he says he will testify of things which he has experienced and which he has seen with his own eyes. It is interesting that in verse 18 he says there are some things which "according to our language, we are not able to write." We don't know whether this is referring to Hebrew or Egyptian. In any event when he tries to record some of the prayers and teachings of Jesus he will say "it cannot be written."