Note, for example, the state of mind of the old Hebrews, I use them merely as an illustration, because you are familiar with their story as told in the Old Testament. Similar things are true of every race on the face of the earth. They knew nothing about the real nature of this universe. They knew nothing about natural forces working in accordance with what we call natural laws. Consequently, they lived in a child- world, a world of magic and miracle, a world in which anything might happen. It did not trouble one of the people of that time to be told that, in answer to the prayer of one of the prophets, an axe-head which had sunk in the water rose and floated on the surface. There were no natural laws in his mind contradicted by an asserted fact like that. It never occurred to him to be troubled about it. There was nothing very startling to him in being told that the sun stood still for an hour or two to enable a general to finish a battle in which he was engaged. He did not know enough about the universe to see what tremendous consequences would be involved in the possibility of a thing like that. He was not troubled when you told him that a man had been swallowed by a great fish, and had lived for three days and three nights in its stomach, and had come out uninjured. There was no improbability in it to him. Simply, a question as to whether God had chosen to have the fish large enough so that it could swallow him. To be told again that a human body that could eat food and digest it, a body like ours, might rise into the air and pass out of sight into some invisible heaven, not very far away, there was nothing incredible about it. He knew nothing about the atmosphere, limited in its range so that it would be impossible to breathe beyond a certain distance from the planet. He knew nothing about the intense cold that would make life impossible just a little way above the surface. The world in which our forefathers lived until modern times was just this magic, Jack-and-the-Beanstalk world, a world without any impossibilities in it, without any improbabilities in it. All this thought of the true and the untrue, the possible and the impossible, the probable and the improbable, is the result of the fact that man has grown up, has left his childhood behind him, has begun to think, has begun to study, has begun to search for reality, to find out the nature of the world in which he lives, the forces with which he must deal, to understand the universe at least in some narrow range, measured by his so-far experience.