George Orwell quote: “The greatest enemy of clear language is insincerity.”

“The great enemy of clear language is insincerity. When there is a gap between one's real and one's declared aims, one turns as it were instinctively to long words and exhausted idioms, like a cuttlefish spurting out ink.”

George Orwell book Politics and the English Language

Source: Politics and the English Language (1946)

“The real problem in speech is not precise language. The problem is clear language.”

Richard Feynman (1918–1988) American theoretical physicist

" New Textbooks for the "New" Mathematics http://calteches.library.caltech.edu/2362/1/feynman.pdf", Engineering and Science volume 28, number 6 (March 1965) p. 9-15 at p. 14
Paraphrased as "Precise language is not the problem. Clear language is the problem."
Context: The real problem in speech is not precise language. The problem is clear language. The desire is to have the idea clearly communicated to the other person. It is only necessary to be precise when there is some doubt as to the meaning of a phrase, and then the precision should be put in the place where the doubt exists. It is really quite impossible to say anything with absolute precision, unless that thing is so abstracted from the real world as to not represent any real thing.Pure mathematics is just such an abstraction from the real world, and pure mathematics does have a special precise language for dealing with its own special and technical subjects. But this precise language is not precise in any sense if you deal with real objects of the world, and it is only pedantic and quite confusing to use it unless there are some special subtleties which have to be carefully distinguished.

“Let me make it very clear to you, it is no doubt that the state language of Pakistan is going to be Urdu and no other language. Anyone who tries to mislead you is really the enemy of Pakistan. Without state language, no nation can remain tied up solidly together and function. Look at the history of every government judgement substitute language. Therefore, so far as the State language is concerned, Pakistan's state language shall be Urdu.”

Muhammad Ali Jinnah (1876–1948) Founder and 1st Governor General of Pakistan

Address to a huge public rally in w:Dhaka, w:East Bengal (then the eastern wing of the w:Dominion of Pakistan and now the independent state of w:Bangladesh) (21 March 1948)