45 ￼ God called upon Cainan in the wilderness in the fortieth year of his age; and he met Adam in journeying to the place Shedolamak. He was eighty-seven years old when he received his ordination.This book is meant to not only give us a timeline of the days of earth, (Adam's birth represented the first day of man's life on earth and his death marked the 930th year of the world) but to also give us a lineage (history) of the priesthood.
￼ 36. For instance, Abel, before he received the assurance from heaven that his offerings were acceptable unto God, had received the important information of his father that such a Being did exist, who had created and who did uphold all things. Neither can there be a doubt existing on the mind of any person, that Adam was the first who did communicate the knowledge of the existence of a God to his posterity; and that the whole faith of the world, form that time down to the present, is in a certain degree dependent on the knowledge first communicated to them by their common progenitor; and it has been handed down to the day and generation in which we live, as we shall show from the face of the sacred records.
Lectures on Faith, Lecture Second
You can play with the numbers and figure out fun things like Noah's father, Lamech was 56 when Adam died. And you might realize that when Adam's testimony was not alone: Adam, Enos, Cainan, Mahalaleel, Jared, Methuselah, Lamech and Noah all lived on the earth at the same time. Also it can be pointed out that Enos, Cainan, Mahaleleel, Jared, Methuselah and Lamech all knew Adam and Noah.
The 5th book of Genesis then shows us not only that the knowledge and faith of God came into the world through the Lord's Holy Priesthood first given to Adam, but that it was preserved, "it was retained in the minds of righteous men,"(Lectures) and it was communicated in righteousness down through "the generations of man." From the time of Adam's creation the truth of man's creation and the existence of God, a true and living God, has been taught by and through the power of God's Priesthood first given to Adam.
23 ￼ And they were preachers of righteousness, and spake and prophesied, and called upon all men, everywhere, to repent; and faith was taught unto the children of men.