Ludwig Wittgenstein
Ludwig Josef Johann Wittgenstein (26 April 1889 – 29 April 1951) was an Austrian
Austrian can refer to:* Someone from Austria or of Austrian descent. See Austrians.* Someone who is considered an Austrian citizen. See Austrian nationality law.* Something associated with the country Austria...

 philosopher who worked primarily in logic
In philosophy, Logic is the formal systematic study of the principles of valid inference and correct reasoning. Logic is used in most intellectual activities, but is studied primarily in the disciplines of philosophy, mathematics, semantics, and computer science...

, the philosophy of mathematics
Philosophy of mathematics
The philosophy of mathematics is the branch of philosophy that studies the philosophical assumptions, foundations, and implications of mathematics. The aim of the philosophy of mathematics is to provide an account of the nature and methodology of mathematics and to understand the place of...

, the philosophy of mind
Philosophy of mind
Philosophy of mind is a branch of philosophy that studies the nature of the mind, mental events, mental functions, mental properties, consciousness and their relationship to the physical body, particularly the brain. The mind-body problem, i.e...

, and the philosophy of language
Philosophy of language
Philosophy of language is the reasoned inquiry into the nature, origins, and usage of language. As a topic, the philosophy of language for analytic philosophers is concerned with four central problems: the nature of meaning, language use, language cognition, and the relationship between language...

. He was professor in philosophy at the University of Cambridge
University of Cambridge
The University of Cambridge is a public research university located in Cambridge, United Kingdom. It is the second-oldest university in both the United Kingdom and the English-speaking world , and the seventh-oldest globally...

 from 1939 until 1947. In his lifetime he published just one book review, one article, a children's dictionary, and the 75-page Tractatus Logico-Philosophicus
Tractatus Logico-Philosophicus
The Tractatus Logico-Philosophicus is the only book-length philosophical work published by the Austrian philosopher Ludwig Wittgenstein in his lifetime. It was an ambitious project: to identify the relationship between language and reality and to define the limits of science...

(1921). In 1999 his posthumously published Philosophical Investigations
Philosophical Investigations
Philosophical Investigations is, along with the Tractatus Logico-Philosophicus, one of the most influential works by the 20th-century philosopher Ludwig Wittgenstein...

(1953) was ranked as the most important book of 20th-century philosophy, standing out as "...the one crossover masterpiece in twentieth-century philosophy, appealing across diverse specializations and philosophical orientations".

"It is necessary to be given the prop that all elementary props are given." This is not necessary because it is even impossible. There is no such prop! That all elementary props are given is SHOWN by there being none having an elementary sense which is not given.

Notes of 1919, as quoted in Ludwig Wittgenstein : The Duty of Genius (1990) by Ray Monk

A proposition is completely logically analyzed if its grammar is made completely clear: no matter what idiom it may be written or expressed in...

Philosophical Remarks (1930), Part I (1)

Tell them I've had a wonderful life.

Last words, to his doctor's wife. (28 April 1951), as quoted in Ludwig Wittgenstein : A Memoir (1966) by Norman Malcolm|Norman Malcolm, p. 100

What is troubling us is the tendency to believe that the mind is like a little man within.

Remarks to John Wisdom|John Wisdom, quoted in Zen and the Work of WIttgenstein by Paul Weinpaul in The Chicago Review Vol. 12, (1958), p. 70

Make sure that your religion is a matter between you and God only.

Comment to Maurice O'Connor Drury|Maurice O'Connor Drury, as quoted in Wittgenstein Reads Freud : The Myth of the Unconscious (1996) by Jacques Bouveresse, as translated by Carol Cosman, p. 14

A serious and good philosophical work could be written consisting entirely of jokes.

As quoted in "A View from the Asylum" in Philosophical Investigations from the Sanctity of the Press (2004), by Henry Dribble, p. 87