--- The concept of ``intentionality''\label{intentionality} originated in medieval philosophy, but was revived by Franz Brentano (1838--1916). It is rather different from what is usually meant by ``intention.'' Brentano suggested that it was the ``ineliminable mark of the mental.'' Our beliefs, for example, are necessarily {\em about\/} something, and Brentano claimed that this is true for all mental phenomena, and no physical phenomena; ``\ldots beliefs, desires, hopes, loves, wonderings, expectings, and so on---are about something; they take an object.''\endnote{\cite[page 61]{OF:TSOTM}} This object is the semantic content of mental states; the fact that they refer to something is what gives our thoughts meaning. The object need not actually exist---we might be thinking about a unicorn, or Santa Claus---but without {\em some\/} object, there is no thought, or anything of the sort. In linguistic terminology, mental events are transitive.--- The citation is Owen Flanagan's book The Science of the Mind.-- Robin