After hearing all God had shown to his father, through prophetic revelation, Nephi desired to obtain a deeper knowledge of what he had heard. As he states in the following passage, he knew there was only one reliable way to obtain that deeper knowledge.
How can a person diligently seek God?
Do you believe you have diligently sought a greater understanding of who God is and what His will is for you? If not, would it be worthwhile to make the effort?
How do you expect the Holy Ghost to work with you as you earnestly seek greater knowledge from God?
Do you believe He will work with you?
Why would God require a certain amount of diligence and effort before extending the gift of the Holy Ghost?