In another chapter I have told you how Roger Bacon, the great genius of the thirteenth century, was prevented for years from writing a single word, lest he get into new troubles with the authorities of the church. And five hundred years later, the contributors to the great philosophic “Encyclopædia” were under the constant supervision of the French gendarmerie. Half a century afterwards, Darwin, who dared to question the story of the creation of man, as revealed in the Bible, was denounced from every pulpit as an enemy of the human race. Even to-day, the persecution of those who venture into the unknown realm of science has not entirely come to an end. And while I am writing this Mr. Bryan is addressing a vast multitude on the “Menace of Darwinism,” warning his hearers against the errors of the great English naturalist. [Illustration: GALILEO] All this, however, is a mere detail. The work that has to be done invariably gets done, and the ultimate profit of the discoveries and the inventions goes to the mass of those same people who have always decried the man of vision as an unpractical idealist. The seventeenth century had still preferred to investigate the far off heavens and to study the position of our planet in relation to the solar system. Even so, the Church had disapproved of this unseemly curiosity, and Copernicus who first of all had proved that the sun was the centre of the universe, did not publish his work until the day of his death. Galileo spent the greater part of his life under the supervision of the clerical authorities, but he continued to use his telescope and provided Isaac Newton with a mass of practical observations, which greatly helped the English mathematician when he discovered the existence of that interesting habit of falling objects which came to be known as the Law of Gravitation. That, for the moment at least, exhausted the interest in the Heavens, and man began to study the earth. The invention of a workable microscope, (a strange and clumsy little thing,) by Anthony van Leeuwenhoek during the last half of the 17th century, gave man a chance to study the “microscopic” creatures who are responsible for so many of his ailments. It laid the foundations of the science of “bacteriology” which in the last forty years has delivered the world from a great number of diseases by discovering the tiny organisms which cause the complaint. It also allowed the geologists to make a more careful study of different rocks and of the fossils (the petrified prehistoric plants) which they found deep below the surface of the earth. These investigations convinced them that the earth must be a great deal older than was stated in the book of Genesis and in the year 1830, Sir Charles Lyell published his “Principles of Geology” which denied the story of creation as related in the Bible and gave a far more wonderful description of slow growth and gradual development.