The teacher's knowledge of children.--Time was when we thought of the child as a miniature man, differing from adults on the physical side only in size and strength, and on the mental side only in power and grasp of thought. Now we know better. We know that the child differs from the adult not only in the _quantity_ but also in the _quality_ of his being. It is the business of the teacher to understand how the child _thinks_. What is the child's concept of God? What is the character of the child's prayer? How does the child _feel_ when he takes part in the acts of worship? We talk to the child about serving God; what is the child's understanding of service to God? We seek to train the child to loyalty to the church; what does the church stand for to the child? We teach the child about sin and forgiveness; just what is the child's comprehension of sin, and what does he understand by forgiveness? We tell the child that he must love God and the Christ; can a child control his affections as he will, or do they follow the trend of his thoughts and experiences? These are not idle questions. They are questions that must be answered by every teacher who would be more than the blind leader of the blind. Coming to know the child.--How shall the teacher come to know the child? Professor George Herbert Palmer sets forth a great truth when he says that the first quality of a great teacher is the quality of _vicariousness_. By this he means the ability on the part of the teacher to step over in his imagination and take the place of the child. To look at the task with the child's mind and understanding, to feel the appeal of a lesson or story through the child's emotions, to confront a temptation with the child's power of will and self-control--this ability is the beginning of wisdom for those who would understand childhood. The teacher must first of all, therefore, be a sympathetic investigator in the laboratory of child life. Not only in the Sunday school, but daily, he must _observe, study, seek to interpret children_. Nor should the teacher of religion neglect the books on the child and his religion. Many investigators are giving their time and abilities to studying child nature and child religion. A mastery of their findings will save us many mistakes in the leadership and training of children. A knowledge of their methods of study will show us how ourselves more intelligently to study childhood. Comprehension of the principles they represent, coupled with the results of our own direct interpretation of children, will convince us that, while each child differs from every other, _certain fundamental laws apply to all childhood_. It is the teacher's task and privilege to master these laws.