Europe's greatest scientist during the latter half of the 17th century, Christiaan Huygens was a towering figure in the fields of astronomy, optics, and mathematics. Among his many achievements, he developed the theory of light travelling as a wave, invented the mechanism for the pendulum clock, and discovered the rings of Saturn via a telescope that he had also invented. Revisiting the Dutch Golden Age—a time of unprecedented intellectual expansion in the Netherlands—Hugh Aldersey-Williams builds a compelling case that Huygens was a crucial figure in scientific history.