“Intellect distinguishes between the possible and the impossible; reason distinguishes between the sensible and the senseless. Even the possible can be senseless.”

Source: The Life of the Mind (1971/1978), p. 14.

... les traités de mécanique ne distinguent pas bien nettement ce qui est expérience, ce qui est raisonnement mathématique, ce qui est convention, ce qui est hypothèse.
Source: Science and Hypothesis (1901), Ch. VI: The Classical Mechanics, Tr. George Bruce Halsted (1913)

Introduction, p. 2.
The Causes of Evolution (1932)

"Hazards of Prophecy: The Failure of Imagination" in Profiles of the Future (1962)

Perhaps the adjective "elderly" requires definition. In physics, mathematics, and astronautics it means over thirty; in the other disciplines, senile decay is sometimes postponed to the forties. There are, of course, glorious exceptions; but as every researcher just out of college knows, scientists of over fifty are good for nothing but board meetings, and should at all costs be kept out of the laboratory!

"Hazards of Prophecy: The Failure of Imagination" in Profiles of the Future (1962; as revised in 1973)
On Clarke's Laws

Source: The Human Condition

James Mirrlees in: Anders Barany, ‎Nobelstiftelsen (1996). Les Prix Nobel. p. 353

Source: Conceptual Structures, 1984, p. 91. cited in: C.J. van Rijsbergen, F. Crestani, M. Lalmas (1998) Information Retrieval: Uncertainty and Logics. p. 59

On The Comedy of Errors, in Ch. XV.
Biographia Literaria (1817)
Context: The myriad-minded man, our, and all men's, Shakespeare, has in this piece presented us with a legitimate farce in exactest consonance with the philosophical principles and character of farce, as distinguished from comedy and from entertainments. A proper farce is mainly distinguished from comedy by the licence allowed, and even required, in the fable, in order to produce strange and laughable situations. The story need not be probable, it is enough that it is possible.

From interview with Anshul Chaturvedi