When Albert Einstein published his first paper on relativity theory, it caused a stir in the physicists' community. When more and more evidence was gathered to prove the theory correct, even laymen became interested in it. Since the theory of relativity uses involved higher mathematics, it is considered notoriously difficult to grasp, and at the time it was published, it was claimed that only 12 people in the world were able to fully understand it. One of these was the Dutch physicist Hendrik Lorentz, who wrote the articles collected in this book for a lay audience. He explains the basics of the theory in clear and concise terms without needing any mathematics. All that is needed to fo follow his arguments is a bit of patience and time.