It is past ten o'clock at night. A little boy fond of going about the country in search of plants has returned home. Finding the door of his father's house locked, and fearing to awaken his parents, he settles down contentedly on the step to spend the night there. Then a woman's hand quietly unbolts the door and receives the little wanderer back. The boy is David Livingstone. Now-a-days we know him as one of the greatest missionary explorers of our times.