The Stoics, who were both pantheists and materialists, present us with a very thorough-going form of fatalism. For them the course of the universe is an iron-bound necessity. There is no room anywhere for chance or contingency. All changes are but the expression of unchanging law. There is an eternally established providence overruling the world, but it is in every respect immutable.
Nature is an unbreakable chain of cause and effect.
Providence is the hidden reason contained in the chain. Destiny or fate is the external expression of this providence, or the instrumentality by which it is carried out. It is owing to this that the prevision of the future is possible to the gods. Cicero, who had written at length on the art of divining the future, insists that if there are gods there must be beings who can foresee the future. Therefore the future must be certain, and, if certain, necessary.