'According to the Tractatus, everything that can be thought can also be said. The limits of language are, therefore, the limits of thought, so that a complete philosophy of the "sayable" will be a complete theory of what Kant had called "understanding". All metaphysical problems arise because of the attempt to say what cannot be said.'
Roger Scruton,
A Short History of Modern Philosophy
'That whereof we cannot speak we must consign to silence.'
Or, I would add, to poetry and music.
Either way, happy birthday, Wittgenstein.