This is an important, foundational principle for gaining Biblical understanding. In the Bible, especially the New Testament, seeing can mean either physical or spiritual sight, and hearing can refer to either physical or spiritual hearing. The physical and the spiritual correspond to knowledge and understanding. Knowledge is a characteristic of the soul, while understanding is of the spirit. The same thing can be said by replacing souland spirit with the words mind and heart respectively.
Knowledge of the Bible is obtained principally by reading, listening to sermons or attending Bible Studies. However, it is an erroneous belief that understanding is acquired by doing the aforementioned activities. Consider the following description of one of Jesus’ post crucifixion appearances to the disciples.
But Thomas, one of the twelve, called Didymus, was not with them when Jesus came. So the other disciples were saying to him, “We have seen the Lord!” But he said to them, “Unless I see in His hands the imprint of the nails, and put my hand into His side, I will not believe.” After eight days His disciples were again inside, and Thomas with them. Jesus came, the doors having been shut, and stood in their midst and said to Thomas, “Reach here with your finger, and see My hands; and reach here your hand and put it into My side, and do not be unbelieving, but believing.” Thomas answered and said to Him, “My Lord and my God!” Jesus said to Him, “Because you have seen Me, have you believed? Blessed are they who did not see, and yet believed.” (John 20:24-29)
When Jesus said, “Blessed are they who did not see, and yet believed,” He made an important statement concerning the two meanings of seeing and hearing. The point He makes is that it is not as important to see Him with our physical eyes, but that He be seen supernaturally with the spiritual eyes of the heart. Seeing and hearing with your spiritual eyes and ears is to understand, and understanding, being spiritual, is acquired by means of a revelation. No amount of knowledge will produce understanding. Knowledge of the Bible is important because it is a physical framework into which understanding is placed. In other words, all understanding you receive by way of revelation must fit into the written word of God. If it doesn’t, it is not a true revelation.