The writer once prosecuted a druggist who had, by mistake, filled a prescription for a one-fourth-grain pill of calomel with a one-fourth-grain pill of morphine. The baby for whom the pill was intended died in consequence. The defence was that the prescription had been properly filled, but that the child was the victim of various diseases, from acute gastritis to cerebro-spinal meningitis. In preparation the writer was compelled to spend four hours every evening for a week with three specialists, and became temporarily a minor expert on children’s diseases. To-day he is forced to admit that he would not know a case of acute gastritis from one of mumps. But the druggist was convicted. Yet it is not enough to prepare for the defence you _believe_ the accused is going to interpose. A conscientious preparation means getting ready for _any_ defence he may endeavor to put in. Just as the prudent general has an eye to every possible turn of the battle and has, if he can, re-enforcements on the march, so the prosecutor must be ready for anything, and readiest of all for the unexpected. He must not rest upon the belief that the other side will concede any fact, however clear it may seem. Some cases are lost simply because it never occurs to the district attorney that the accused will deny something which the State has twenty witnesses to prove. The twenty witnesses are, therefore, not summoned on the day of trial, the defendant _does_ deny it, and as it is a case of word against word the accused gets the benefit of the doubt and, perhaps, is acquitted. No case is properly prepared unless there is in the court-room every witness who knows anything about any aspect of the case. No one can foretell when the unimportant will become the vital. Most cases turn on an unconsidered point. A prosecutor once lost what seemed to him the clearest sort of a case. When it was all over, and the defendant had passed out of the court-room rejoicing, he turned to the foreman and asked the reason for the verdict. “Did you hear your chief witness say he was a carpenter?” inquired the foreman. “Why, certainly,” answered the district attorney. “Did you hear me ask him what he paid for that ready-made pine door he claimed to be working on when he saw the assault?” The prosecutor recalled the incident and nodded. “Well, he said ten dollars—and I knew he was a liar. A door like that don’t cost but four-fifty!” It is, perhaps, too much to require a knowledge of carpentry on the part of a lawyer trying an assault case. Yet the juror was undoubtedly right in his deduction.