“Language always betrays us, tells the truth when we want to lie, and dissolves into formlessness when we would most like to be precise.”

Source: His Dark Materials, The Subtle Knife (1997), Ch. 4 : Trepanning
Context: Lyra sighed; she had forgotten how roundabout Scholars could be. It was difficult to tell them the truth when a lie would have been so much easier for them to understand.

Theogony, lines 28–29
Translations, Works and Days and Theogony (1993)

Source: Friends, Lovers, Chocolate

Pablo Picasso said something very similar. Perhaps it is the source? From Herschel B. Chipp’s Theories of Modern Art: "We all know that Art is not truth. Art is a lie that makes us realize truth, at least the truth that is given us to understand."
Disputed

Reply when asked if he thought he was a lot like the character he plays in Big Fish in an interview with Paul Fischer at Dark Horizons (2 December 2003).

1860s, Our Composite Nationality (1869)
Context: It is objected to the Chinaman that he is secretive and treacherous, and will not tell the truth when he thinks it for his interest to tell a lie. There may be truth in all this; it sounds very much like the account of man’s heart given in the creeds. If he will not tell the truth, except when it is for his interest to do so, let us make it for his interest to tell the truth. We can do it by applying to him the same principle of justice that we apply to ourselves. But I doubt if the Chinese are more untruthful than other people. At this point I have one certain test. Mankind are not held together by lies. Trust is the foundation of society. Where there is no truth, there can be no trust, and where there is no trust, there can be no society. Where there is society, there is trust, and where there is trust, there is something upon which it is supported. Now a people who have confided in each other for five thousand years; who have extended their empire in all directions until it embraces one-fifth of the population of the globe; who hold important commercial relations with all nations; who are now entering into treaty stipulations with ourselves, and with all the great European powers, cannot be a nation of cheats and liars, but must have some respect for veracity. The very existence of China for so long a period, and her progress in civilization, are proofs of her truthfulness. This is the last objection which should come from those who profess the all-conquering power of the Christian religion. If that religion cannot stand contact with the Chinese, religion or no religion, so much the worse for those who have adopted it. It is the Chinaman, not the Christian, who should be alarmed for his faith. He exposes that faith to great dangers by exposing it to the freer air of America. But shall we send missionaries to the heathen to right to come to us? I think a few honest believers in the teachings of Confucius would be well employed in expounding his doctrines among us.

Source: Plan B: Further Thoughts on Faith

Other