And I will tell you that which no man knoweth save me and thee alone—
I learned an interesting lesson recently listening to a talk by Elder Dieter F. Uchtdorf.
Sections 15 and 16 of the Doctrine & Covenants are the same in wording. However, they are blessings given to two different people—Peter and John Whitmer. They are at once the same and intimately different.
In many cases, the commands and directions of the Lord are universal. We are all His children and all have the same charge and responsibilities. But in very important ways, we are all uniquely different and individual. That’s why this verse, to each of them separately, is so profound.
The Lord knows us personally. He teaches us the things we need to know personally. Through the gift and companionship of the Holy Ghost, He will tell us the things we need to know.
His work and glory is to bring to pass the individual salvation of His children. So while He has universal laws that govern the universe, He will give us the direction that is between Him and us alone. We just have to be worthy of it and seek it diligently. He will provide what we need.