A       Storm Clouds Gather

The ’perennial foundations of thinking’ are presented: Newton’s concepts of space, time and inertial mass. Also following Newton we define inertial frames of reference. Next we present Galileo’s formulation of the relativity of uniform movement. The principle of relativity is formulated based on the concept of an inertial frame. In the third section we show that Maxwell's theory of electromagnetism does not fit with Newton's mechanics and Galileo’s equivalence of all inertial frames: Newton and Galileo’s manner of adding velocities shows itself to be in conflict with the constancy of the speed of light. The fourth section presents Einstein’s approach to solving this conflict. Finally we take a short detour to other fields of activity, for which around 1900 storm clouds began to gather.