The following Essay does not pretend to establish a new theory. Its object is to examine certain typical notions of truth, one or other of which — whether in the form of a vague assumption, or raised to the level of an explicit theory — has hitherto served as the basis of philosophical speculation. If I am not mistaken, every one of these typical notions and accredited theories of truth fails sooner or later to maintain itself against critical investigation. And I have tried, whilst exhibiting the nature and the grounds of their failure.