 Popper accordingly argues that it is a fundamental mistake for the historicist to take the unconditional scientific prophecies of eclipses as being typical and characteristic of the predictions of natural science; they are possible only because our solar system is a stationary and repetitive system which is isolated from other such systems by immense expanses of empty space. Human society and human history are not isolated systems and are continually undergoing rapid, non-repetitive development. In the most fundamental sense possible, every event in human history is discrete, novel, quite unique, and ontologically distinct from every other historical event. For this reason, it is impossible in principle that unconditional scientific prophecies could be made in relation to human history—the idea that the successful unconditional prediction of eclipses provides us with reasonable grounds for the hope of successful unconditional prediction regarding the evolution of human history turns out to be based upon a gross misconception. As Popper succinctly concludes, “The fact that we predict eclipses does not, therefore, provide a valid reason for expecting that we can predict revolutions” (1963: 340).