(1) _The General Principle._ All good work involves the prerequisite of training. Especially is this true of teaching; and there is a reason why the principle holds with regard to the Sunday-school teacher even more directly than with the secular teacher. While the subjects of teaching are vitally important, relating to character and efficient service, the time for teaching is short, less than an hour each week, in contrast to the twenty or twenty-five hours in the week-day school. To make an impression in so short a teaching period, with such long intervals between the lessons, demands that the teacher be one who possesses exceptional fitness for his work, and this superior fitness cannot be obtained without special and thorough training. (2) _The Teacher's Responsibility._ All-important as is the work of religious teaching, for which the Bible is the chief text-book in the church, there is but one institution in our time charged with that mighty duty, and that is the Sunday school. The Bible is rarely taught in the home, which should be the first place for teaching it; it is only incidentally taught in the pulpit, of which the aim is not so much instruction as inspiration. Practically all the teaching of the Bible now devolves upon the Sunday school, and the Sunday school only. If the Sunday schools of the world for one generation should fail to teach the word of life, the knowledge of that word would well-nigh cease. And the one person charged with that task, the one on whom the responsibility rests, is the Sunday-school teacher. He who is intrusted with so great a work, and upon whose fidelity the work depends, must have a proper equipment; and that equipment presupposes training. (3) _The Demand of the Age._ We are living in an intellectual age, unparalleled in the history of the world. The boundaries of knowledge in every direction have widened, and in each realm the search is deeper and more thorough. Such wealth has been added through recent investigations to the store of Bible knowledge that most commentaries, expositions, and introductions of the past have now but slight value. Another exceedingly important realm that has been added to the domain of knowledge is that of child study, but recently an unexplored field, now open to every reader. In such a time as this the teacher who would impart the contents of the Bible to the young must have eyes and mind opened. He must know the results of modern investigation in the Scriptures and in the nature of those whom he teaches. His pupils are under the care of trained and alert specialists through the week; they must receive instruction from well-taught minds in the Sunday school.