Only two quotes by Ludwig Wittgenstein
Ludwig Josef Johann Wittgenstein (6 April 1889 – 29 April 1951) was an Austrian-born philosopher who spent much of his life in England. He worked primarily in logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language. He is considered by some to be the greatest philosopher of the 20th century.
About what one cannot speak, one must remain silent.
Wovon man nicht sprechen kann, darüber muss man schweigen.
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The world of the happy is quite different from the world of the unhappy.
Die Welt des Glücklichen ist eine andere als die des Unglücklichen.
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The author info is from Wikipedia, licensed under the GNU Free Documentation License.
The original picture is by Moritz Nähr, Public domain, via Wikimedia Commons and may have been cropped and converted to greyscale.