It was his inviolable sense of duty, and his indefeasible conviction that his Father in heaven would not forsake him whilst pursuing a course in obedience to his will, and designed to advance the welfare of his children. As this furnishes the key to Livingstone's future life, and the answer to one of the most serious objections ever brought against it, it is right to spend a little time in elucidating the principles by which he was guided. There was a saying of the late Sir Herbert Edwardes which he highly valued: "He who has to act on his own responsibility is a slave if he does not act on his own judgment." Acting on this maxim, he must set aside the views of others as to his duty, provided his own judgment was clear regarding it. He must even set aside the feelings and apparent interest of those dearest to him, because duty was above everything else. His faith in God convinced him that, in the long run, it could never be the worse for him and his that he had firmly done his duty. All true faith has in it an element of venture, and in Livingstone's faith this element was strong. Trusting God, he could expose to venture even the health, comfort, and welfare of his wife and children. He was convinced that it was his duty to go forth with them and seek a new station for the Gospel in Sebituane's country. If this was true, God would take care of them, and it was "better to trust in the Lord than to put confidence in man." People thoughtlessly accused him of making light of the interests of his family. No man suffered keener pangs from the course he had to follow concerning them, and no man pondered more deeply what duty to them required. But to do all this, Livingstone must have had a very clear perception of the course of duty. This is true. But how did he get this? First, his singleness of heart, so to speak, attracted the light: "If thine eye be single, thy whole body shall be full of light." Then, he was very clear and very minute in his prayers. Further, he was most careful to scan all the providential indications that might throw light on the Divine will. And when he had been carried so far on in the line of duty, he had a strong presumption that the line would be continued, and that he would not be called to turn back. It was in front, not in rear, that he expected to find the pillar of cloud and the pillar of fire. In course of time, this hardened into a strong instinctive habit, which almost dispensed with the process of reasoning.