The world is made up of facts, not things.
A tautology's truth is certain, a proposition's possible, a contradiction's impossible.
Nothing is more important for teaching us to understand the concepts we have than to construct fictitious ones.
One can mistrust one's own senses, but not one's own belief.
A picture is a model of reality.
That which cannot be said must not be said. That which cannot be said, one must be silent thereof.