  William thinks, in fact, that to call the world eternal in the aforementioned sense is not to use the term “eternal” in its strictest sense. Accordingly, he starts by explaining different senses of the term in the first extended treatment of the distinction between eternity and time in the middle ages. He then presents and refutes arguments that the world has no beginning, and provides his own positive arguments that the world must have a temporal beginning, a first instant of its existence.