These examples will suffice, though volumes of them could be written. They show us clearly a twofold certainty. The difference between the natural and scientific certainty is not that the former is a blind conviction formed at random, but only that one is not clearly conscious of the reasons on which it rests, whereas this is the case in scientific certitude. We see further the untrained power of the intellect manifest itself in natural knowledge and certainty; for this purpose it is primarily created; philosophical thought is difficult for it, and many have no talent at all for it. It is also unfailing in apprehending directly things pertaining to human life. Here the mind is free of that morbid scepticism of which it too easily becomes a prey when it begins to investigate and probe scientifically. What it there sees with certainty cannot always be found here distinctly, and thus the mind begins to doubt things it was hitherto sure of, and which often remain instinctively certain to the mind despite its artificial doubts. Now we can also understand why philosophers so often have doubts which to the untrained look absurd, and why philosophers differ in their opinions on most important things, whereas mankind guided by its natural certitude is unanimous in them. This certainty is destined to be the reliable guide of man through life. It precedes science, and can even exist without it. Long before there was a science of art and of jurisprudence the Babylonians and Egyptians had built their monuments, and _Solon_ and _Lycurgus_ had given their wise laws. And long before philosophers were disputing about the moral laws, men had the right view in regard to virtue and vice (cf. _Cicero_, De Oratore, I, 32). The same certitude is also destined to guide man in the more important questions, in the questions of religion and morality. The Creator of human nature and its destiny, who implanted instinct in the animal to guide it unconsciously in the necessities of life, has also given to man the necessary light to perceive with certainty truths without which it would be impossible to live a life worthy of man. It is just this natural knowledge and certitude that gives man certainty of divine revelation, after God vouchsafed to give it to mankind for its unfailing guidance and help. For revelation was not only intended for theologians, Bible critics, philosophers, and Church-historians, but for all. And God has taken care, as He had to do, that man has ample evidence that God has spoken, and that the Church is the authorized Guardian of this revelation, even without critical research in history and philosophy. We have elsewhere briefly stated this evidence in the words of the Vatican Council.