And it was so, that when he had turned his back to go from Samuel, God gave him another heart: and all those signs came to pass that day. (1 Samuel 10:9)
The Lord would not leave Saul to be placed in a position of trust without divine enlightenment. He was to have a new calling, and the Spirit of the Lord came upon him. The effect was that he was changed into a new man. The Lord gave Saul a new spirit, other thoughts, other aims and desires than he had previously had. This enlightenment, with the spiritual knowledge of God, placing him on vantage ground, was to bind his will to the will of Jehovah (Letter 12a, 1888).