Alētheia

The hidden etymology

The Greek word for truth, alētheia (ἀλήθεια), is built on a striking image. It joins the negating prefix a- ('not', 'un-') to lēthē (λήθη), 'forgetting', 'concealment', 'oblivion' — the same word as the river Lethe in the underworld, whose waters made the dead forget. Truth, on the surface of the word itself, is therefore the un-forgotten, the un-concealed: not so much a correct statement as a bringing of things out of hiddenness into the light. The related verb lanthanō means 'to escape notice, to lie hidden'; alētheia is the lifting of that veil.

Truth and the Forms

For Plato truth in the fullest sense belongs to the Forms, the changeless realities, and above all to the Good, which is the source of the truth of all that is known. The soul that turns from the shadows of the cave toward the light is moving toward alētheia — toward what genuinely and always is, as opposed to the shifting half-real things of sense. Knowledge (recollection of the Forms) is the soul's recovery of a truth it had let fall into forgetting; learning is a kind of un-forgetting, which the etymology quietly mirrors.

An idea revived

The buried sense of alētheia as 'unconcealment' was famously brought back to light in the twentieth century by the philosopher Martin Heidegger, who took truth to be primarily the disclosure of beings — their stepping out of hiddenness — rather than the mere agreement of a proposition with a fact. Whatever one makes of his use of it, the reading draws on something genuinely present in the Greek word: that to speak the truth is to let what is show itself as it is.