 A state of affairs is transient if, and only if, it obtains at one time and not another. For instance, the state of affairs Socrates’s not drinking hemlock obtains at some times, but not at others. Transient states of affairs are only possible, actual etc. relative to a time. Before 399 BC it was possible that Socrates does not drink hemlock, but this is no longer possible after 399 BC. A state of affairs is nontransient if, and only, if it is such that necessarily if it obtains at one time it obtains at all times. For example, the state of affairs Socrates’s being hungry on the 15th of April 400 BC at 16:15 is nontransient.