Turning to the sphere of scientific research, we find electricity playing a role in the development of modern thinking remarkably similar to its part as a labour-force in everyday life. We find it associated with phenomena which, in Professor Heisenberg's words, expose their mutual connexions to exact mathematical thinking more readily than do any other facts of nature; and yet the way in which these phenomena have become known has played fast and loose with mathematical thinking to an unparalleled degree. To recognize that in this sphere modern science owes its triumphs to a strange and often paradoxical mixture of outer accident and error in human thought, we need only review the history of the subject without prejudice. * The discovery of electricity has so far been accomplished in four clearly distinct stages. The first extends from the time when men first knew of electrical phenomena to the beginning of the natural scientific age; the second includes the seventeenth and the greater part of the eighteenth centuries; the third begins with Galvani's discovery and closes with the first observations of radiant electricity; and the fourth brings us to our own day. We shall here concern ourselves with a few outstanding features of each phase, enough to characterize the strange path along which man has been led by the discovery of electricity. Until the beginning of modern times, nothing more was known about electricity, or of its sister force, magnetism, than what we find in Pliny's writings. There, without recognizing a qualitative distinction between them, he refers to the faculty of rubbed amber and of certain pieces of iron to attract other small pieces of matter. It required the awakening of that overruling interest in material nature, characteristic of our own age, for the essential difference between electric and magnetic attraction to be recognized. The first to give a proper description of this was Queen Elizabeth's doctor, Gilbert. His discovery was soon followed by the construction of the first electrical machine by the German Guericke (also known through his invention of the air pump) which opened the way for the discovery that electricity could be transmitted from one place to another.