Parmenides believed that all Being is what he called the One, and denied absolutely the possibility of change. He believed that the cosmos is full (i. e., no void), uncreated, eternal, indestructible, unchangeable, immobile sphere of being, and all sensory evidence to the contrary is illusory. One Parmenidean fragment stated, "Either a thing is or it is not," meaning that creation and destruction is impossible.

p. 286 - Before Galileo, The Birth of Modern Science in Medieval Europe (2012)