"If ye continue in my word, then are ye my disciples indeed, and ye shall know the truth, and the truth shall make you free" (John 8:31-32)
Truth must be understood by inward illumination. Then we know the truth. Until that time, we do not know it.
I heard through missionaries of a boy overseas who had memorized Jesus' entire Sermon on the Mount. He did it in such record time and with such apparently little effort that someone called him in to find out how he had done it.
"Well," said the boy, "I would memorize a verse and then trust God to help me put it into practice. Then I would memorize the next verse and say, "Lord, help me to live this one, too."
That boy had truth on his side. He did not consider truth to be something objective, simply to be filed in the mind as knowledge. Rather, truth to him was also subjective - to be acted on.
Truth becomes real to us within our beings by obedience and faith.
Before we can truly obey Him, we must fully receive Him and be so united with Him that His interests are ours and His will is just the expression of our inmost being.
~A. W. Tozer~