It was about his twentieth year that the great spiritual change took place which determined the course of Livingstone's future life. But before this time he had earnest thoughts on religion. "Great pains," he says in his first book, "had been taken by my parents to instill the doctrines of Christianity into my mind, and I had no difficulty in understanding the theory of a free salvation by the atonement of our Saviour; but it was only about this time that I began to feel the necessity and value of a personal application of the provisions of that atonement to my own case[5]." Some light is thrown on this brief account in a paper submitted by him to the Directors of the London Missionary Society in 1838, in answer to a schedule of queries sent down by them when he offered himself as a missionary for their service. He says that about his twelfth year he began to reflect on his state as a sinner, and became anxious to realize the state of mind that flows from the reception of the truth into the heart. He was deterred, however, from embracing the free offer of mercy in the gospel, by a sense of unworthiness to receive so great a blessing, till a supernatural change should be effected in him by the Holy Spirit. Conceiving it to be his duty to wait for this, he continued expecting a ground of hope within, rejecting meanwhile the only true hope of the sinner, the finished work of Christ, till at length his convictions were effaced, and his feelings blunted. Still his heart was not at rest; an unappeased hunger remained, which no other pursuit could satisfy. [Footnote 5: _Missionary Travels_, p.4] In these circumstances he fell in with Dick's _Philosophy of a Future State_. The book corrected his error, and showed him the truth. "I saw the duty and inestimable privilege _immediately_ to accept salvation by Christ. Humbly believing that through sovereign mercy and grace I have been enabled so to do, and having felt in some measure its effects on my still depraved and deceitful heart, it is my desire to show my attachment to the cause of Him who died for me by devoting my life to his service."