(3) _Methods Adapted._ Almost every community, whether in city or in country, possesses some traits peculiar to itself. There may be two towns ten miles apart, one the wealthy residential suburb of a city, the other a settlement surrounding a great factory. The population of these two places will be in marked contrast, and the methods of Christian work successful in one will utterly fail in the other. One street or avenue in a city may mark the boundary line between family churches and mission churches. Within ten minutes' walk of each other may stand two churches of the same denomination, yet so utterly apart in spirit as to possess nothing in common but name. It is possible that each of these two organizations might learn something from the other, and might do their Master's work better by a closer community of interest and feeling. Yet it would be a mistake to introduce into either church all the plans that are successful in the other; or to reject in one Sunday school any method because it has proved a failure in another and a different field. The work of each church and Sunday school must be adapted to the population from which its membership is to be drawn. 2. =The Changing Population.= One of the most imperative questions confronting the gospel worker, both in the church and the Sunday school, arises from the constant changes taking place in our population. In the cities we see stately churches, once thronged, now well-nigh desolate, while their walls echo to the tread upon the sidewalk of a churchless multitude. In front of a fine old church, where once millionaires worshiped, the writer has often passed a news-stand upon which are for sale newspapers in seven different languages. And too often one finds that the churches of a generation ago have been turned into low theaters, or torn down, giving place to stores and office buildings. The general principle may be laid down, that a church in the city almost never lives more than one generation in the same building and with the same character. After thirty years as the very longest period, if it is to retain its members, it must follow them in the march up-town; or if it is to retain its location and still hold a congregation it must seek an absolutely new constituency, and to this end must transform its methods of work. Nor are these migrations of population confined to the city. The towns and villages are governed by the same law of change. A village, once the seat of quiet homes, is suddenly turned into a factory town, with a new and strange population. The farms on country roads, abandoned by the families that formerly tilled them, are occupied by foreigners of alien speech and manners. The building of a railroad will open new towns, and at the same time will make more than one deserted village. These changes in population must be considered in their relation to the work of the Sunday school. The movement will be characterized by varied traits in different places.