“Scepticism is not irrefutable, but obviously nonsensical, when it tries to raise doubts where no questions can be asked.
For doubt can exist only where a question exists, a question only where an answer exists, and an answer only where something can be said.”

Source: Fool's Errand

Source: Tractatus Logico-Philosophicus

1940s, Religion and Science: Irreconcilable? (1948)
Context: Does there truly exist an insuperable contradiction between religion and science? Can religion be superseded by science? The answers to these questions have, for centuries, given rise to considerable dispute and, indeed, bitter fighting. Yet, in my own mind there can be no doubt that in both cases a dispassionate consideration can only lead to a negative answer. What complicates the solution, however, is the fact that while most people readily agree on what is meant by "science," they are likely to differ on the meaning of "religion."

Source: The Case for Faith: A Journalist Investigates the Toughest Objections to Christianity

Source: Sweet Bird of Youth

Source: Life, the Truth, and Being Free (2010), p. 110

47 : The Question and its Answer, p. 78.
The Everything and the Nothing (1963)

Canto II, stanza 27; this can be compared to: I came to the place of my birth, and cried, "The friends of my youth, where are they?" And echo answered, "Where are they?", Anonymous Arabic manuscript
The Bride of Abydos (1813)