To those who are not directly concerned with the attack on supernaturalism it may also be a matter of regret that so much of this work is concerned with a criticism of religious beliefs. But that is an accident of the situation. We have not yet reached that stage in affairs when we can afford to let religion alone, and one may readily be excused the suspicion that those who, without believing in it, profess to do so, are more concerned with avoiding a difficult, if not dangerous, subject, than they are with the problem of developing sane and sound methods of thinking. And while some who stand forward as leaders of popular thought fail to do their part in the work of attacking supernaturalistic beliefs, others are perforce compelled to devote more time than they would otherwise to the task. That, in brief, is my apology for concerning myself so largely with religious topics, and leaving almost untouched other fields where the Freethought attitude would prove equally fruitful of results. After all, it is the mental attitude with which one approaches a problem that really matters. The man or woman who has not learned to set mere authority on one side in dealing with any question will never be more than a mere echo, and what the world needs, now as ever, is not echoes but voices. Information, knowledge, is essential to the helpful consideration of any subject; but all the knowledge in the world will be of very little real help if it is not under the control of a right method. What is called scientific knowledge is, to-day, the commonest of acquisitions, and what most people appear to understand by that is the accumulation of a large number of positive facts which do, indeed, form the raw material of science. But the getting of mere facts is like the getting of money. The value of its accumulation depends upon the use made thereof. It is the power of generalization, the perception and application of principles that is all-important, and to this the grasp of a right method of investigation, the existence of a right mental attitude, is essential.