If a man is morally colour-blind he is likely to be wrong conscientiously. That faculty or element in our nature which we call "conscience" is set within us as a monitor, not as a teacher, in the school of morals. Conscience tells us that we ought to do right, but conscience does not tell us what right is. The compass is safe to steer by as long as its needle points where it ought to point; but the compass needle may be forcibly deflected from the pole, or it may be drawn aside by the influences of its surroundings, and then, of course, it is untrustworthy. It would be well if all of us understood just how far from the true meridian our moral compass-needles were deflected by the attractions of gold or pleasure or appetite or ambition or love or hatred or by the social atmosphere of our immediate neighbourhood.
In Shoes and rations for a long march (Chaplain's talks)