Leucippus
Leucippus (early 5th century BC), one of the atomists, along with other philosophers of his time, made attempts to reconcile this monism with the everyday observation of motion and change. He accepted the monist position that there could be no motion without a void. The void is the opposite of being. It is not-being. On the other hand, there exists something known as an absolute plenum, a space filled with matter, and there can be no motion in a plenum because it is completely full. But, there is not just one monolithic plenum, for existence consists of a multiplicity of plenums. The void must exist to allow this to happen, or else the "frozen world" of Parmenides must be accepted.
Bertrand Russell points out that this does not exactly defeat the argument of Parmenides but, rather, ignores it by taking the rather modern scientific position of starting with the observed data (motion, etc.) and constructing a theory based on the data, as opposed to Parmenides' attempts to work from pure logic. Russell also observes that both sides were mistaken in believing that there can be no motion in a plenum, but arguably motion cannot start in a plenum. Cyril Bailey notes that Leucippus is the first to say that a "thing" (the void) might be real without being a body and points out the irony that this comes from a materialistic atomist. Leucippus is therefore the first to say that "nothing" has a reality attached to it.
Eastern philosophy
The understanding of 'nothing' varies widely between cultures, especially between Western and Eastern cultures and philosophical traditions. For instance, Śūnyatā (emptiness), unlike "nothingness", is considered to be a state of mind in some forms of Buddhism. Achieving 'nothing' as a state of mind in this tradition allows one to be totally focused on a thought or activity at a level of intensity that they would not be able to achieve if they were consciously thinking. A classic example of this is an archer attempting to erase the mind and clear the thoughts to better focus on the shot. Some authors have pointed to similarities between the Buddhist conception of nothingness and the ideas of Martin Heidegger and existentialists like Sartre, although this connection has not been explicitly made by the philosophers themselves.
In some Eastern philosophies, the concept of "nothingness" is characterized by an egoless state of being in which one fully realizes one's own small part in the cosmos.