When a thing has to be attempted, one must never think about possibility or impossibility. Faced with an optional question in an examination paper, one considers whether one can do it or not: faced with a compulsory question, one must do the best one can. You may get some marks for a very imperfect answer: you will certainly get one for leaving the question alone…[sinlessness] will not be attained by any merely human efforts. You musk ask for God’s help.