Now it is very difficult, indeed, for you to persuade a man that he ought to do right under such circumstances. He is ready to doubt and question as to whether these laws of right are imperative, whether they are divine, whether they may not be waived one side in the interest of the thing which he desires to do. So you must guard yourself very carefully, no matter what the department of life may be that you are facing, if you find yourself doubting under the impulse of your own wishes, if you are trying to argue yourself into the belief that you may be permitted to do something which you very much want to do. Be suspicious of your doubts, then, and remember that probably they are wrong. Great moral questions may be involved, and doubt may mean wreck here. There is another field where doubt is dangerous and presumably an evil. You will find most people, in regard to any question which they have considered or which has touched them seriously, with their minds already made up. They have some sort of a persuasion about it, they have a theory which they have accepted; and, if you bring them a truth with ever such overwhelming credentials which clashes with this preconceived idea or prejudice, the chances are that it would be met with doubt, with denial, not a clear-cut, intelligent, well- balanced doubt, but a doubt that springs out of the unwillingness that a man feels to reconstruct his theory. Let me give you an illustration of what I mean, and this away off in another department of life from our own, so that it will not clash with any of your particular prejudices. Sir Isaac Newton won a great and world-wide renown, and magnificently deserved, by his grand discovery of the law of gravity. You will see, then, how natural it was for people to pay deference to his opinion, to be prejudiced in favor of his conclusions. It was perfectly natural and, within certain limits, perfectly right. Sir Isaac Newton not only propounded this law of gravity, but he propounded a theory of light which the world has since discovered to be wrong. But it was universally accepted because it was his. It became the accepted scientific theory of the time. By and by a man, unknown up to that time, by the name of Young, studied Newton's theory, and became convinced that it was wrong; and he propounded another theory, the one which to- day is universally accepted through the civilized world. But it was years before it could gain anything like adequate or fair consideration, because the preconception in favor of Newton's theory stood in the way of any adequate consideration of the one which was subsequently universally adopted.