Ludwig Wittgenstein
The limits of my language mean the limits of my world.
Misconceptions
"Whereof one cannot speak, thereof one must be silent" means: don't talk about what you don't know.
It is not about ignorance, but about the limits of meaningful language. What cannot be said is ethics, the meaning of life, "the mystical": for him, precisely what matters most. Even if all scientific questions were answered, "the problems of life have still not been touched at all".
For Wittgenstein, ethics and religion are unimportant nonsense.
He does say that their sentences are, strictly speaking, nonsense. But he adds that they are a document of a tendency in the human mind which he cannot help "respecting deeply" and would not "for my life ridicule".
The later Wittgenstein completely disowns the earlier one.
He recognises "grave mistakes" in the Tractatus, above all the idea of a general form of all propositions. But he wants both books published together, because the new thoughts can only be understood by contrast with the old ones. And one idea remains: philosophy is not a theory but an activity.
Wittgenstein was a logical positivist of the Vienna Circle.
The Vienna Circle read the Tractatus as a manifesto against metaphysics, and Wittgenstein talked with some of its members. But he never belonged to it, and he cared about what the positivists left aside: "There is indeed the inexpressible. This shows itself; it is the mystical."