Complex sentence: The expression was used as early as 1966 by Arnold M. Ludwig and brought into common usage from 1969 by Charles Tart: it describes induced changes in one's mental state, almost always temporary.
Split into simpler sentences: The expression was used as early as 1966 by Arnold M. Ludwig and brought into common usage from 1969 by Charles Tart. It describes induced changes in one's mental state, almost always temporary.