When the 23-year-old Heber J. Grant was installed as president of the Tooele Stake, he told the Saints he believed the gospel was true. President Joseph F. Smith, a counselor in the First Presidency, inquired, “Heber, you said you believe the gospel with all your heart, … but you did not bear your testimony that you know it is true. Don’t you know absolutely that this gospel is true?”
Heber answered, “I do not.” Joseph F. Smith then turned to John Taylor, the President of the Church, and said, “I am in favor of undoing this afternoon what we did this morning. I do not think any man should preside over a stake who has not a perfect and abiding knowledge of the divinity of this work.”
President Taylor replied, “Joseph, Joseph, Joseph, [Heber] knows it just as well as you do. The only thing that he does not know is that he does know it.” ("Knowing That We Know". Douglas L. Callister. Oct 2007)
Within a few weeks that testimony was realized, and young Heber J. Grant shed tears of gratitude for the perfect, abiding, and absolute testimony that came into his life.
I was reminded of this great story when I listened to How Do I Know If I Know? by John Bytheway. I loved the book. It had great insight.