1. _Unity of thought._ Each occasion of worship should ordinarily have one leading, pervading, governing thought which shall individualize that occasion and distinguish it from others. By this it is not meant that the subject should always be advertised in the hymns and Scriptures and prayers that precede the sermon; this might be unfortunate, as interfering with the purpose of general worship. But all parts of the service should be consistent with the subject of the discourse, and should flow naturally into it; if possible, nothing should be allowed to enter which may divert from it. The assembly should be dismissed filled with one subject and bearing away one great thought. On this account it is usually better to exclude all other subjects, both during and immediately following public worship, and when a subject out of the usual order is to be presented, such as some benevolent object, to give up the entire service to that and concentrate attention on it. 2. _Sustained interest._ The interest should rise with the progress of the service, and find its highest point at the close; otherwise, the good impressions made in the earlier part are lost in the weariness and apathy of the later. Failure in sustaining interest to the end may result from several causes: (1.) Imperfect preparation, so that the matter of the service is commonplace and uninteresting. In this age of intense mental activity, a want of freshness, vigor, and variety of thought is at once felt by the people, and the attention is lost. (2.) Defective, monotonous delivery, which often destroys the force of the best thought. For this the only remedy is persistent training, taken, if possible, under a good elocutionist; and where such a defect exists, to apply this remedy seems clearly the imperative duty of a man whose success in his work depends on power in public speech. (3.) Wearisome protraction of the exercises. Few sermons hold the interest of a congregation beyond half an hour. The effect of the first thirty minutes is in most cases destroyed by seeking to force attention through another fifteen or twenty. (4.) Too great exhaustion of the physical and nervous force of the preacher before the service in preparing for it. The pastor should secure thorough rest of body and mind before the Lord's Day services, so as to come to them fresh and strong. It is better to leave the sermons unfinished than to fail of this. Preserve at all hazards a high tone of physical vigor and a healthful, elastic nervous organism; otherwise, the speaking will lack force and magnetism, and the most able and elaborate sermon will fall flat and powerless. Some of the most successful preachers avoid all severe study on Saturday, making that a day of rest and recreation, that they may come to their Lord's Day work with full nervous and physical vigor.