The four selected ailments are: UNSUBDUED SIN; UNANSWERED PRAYER; PERSISTENT DARKNESS and HABITUAL UNBELIEF. All the brethren who have anything to do with Convention teaching will agree that these are some of the most desperate kinds of difficulty we have to deal with, and we are perpetually coming into contact with them. Somewhat as a physician puts before his class a series of representative cases of disease, and seeks to show how, according to...