 LOTH emerged gradually through the writings of Augustine, Boethius, Thomas Aquinas, John Duns Scotus, and many others. William of Ockham offered the first systematic treatment in his Summa Logicae (c. 1323), which meticulously analyzed the meaning and structure of Mentalese expressions. LOTH was quite popular during the late medieval era, but it slipped from view in the sixteenth and seventeenth centuries. From that point through the mid-twentieth century, it played little serious role within theorizing about the mind.