“Some friendships last as long as convenience lasts.”

Source: Some Do Not ... & No More Parades

Source: The Picture of Dorian Gray

Source: The Book Thief

A Few Maxims for the Instruction of the Over-Educated (1894)

Last words, 19 March, 1702; Quoted in: Herbert Lockyer (1969). 700 Final Quotes from the Famous, the Infamous, and the Inspiring Figures of History. p. 83.
William III, suffering from a broken collar-bone, was speaking to his physician.

Source: The Joys of Love

Progress, Coexistence and Intellectual Freedom (1968), Dangers, Police Dictatorships
Context: Fascism lasted twelve years in Germany. Stalinism lasted twice as long in the Soviet Union. There are many common features but also certain differences. Stalinism exhibited a much more subtle kind of hypocrisy and demagogy, with reliance not on an openly cannibalistic program like Hitler's but on a progressive, scientific, and popular socialist ideology.
This served as a convenient screen for deceiving the working class, for weakening the vigilance of the intellectuals and other rivals in the struggle for power, with the treacherous and sudden use of the machinery of torture, execution, and informants, intimidating and making fools of millions of people, the majority of whom were neither cowards nor fools. As a consequence of this "specific fea­ture" of Stalinism, it was the Soviet people, its most active, talented, and honest representatives, who suffered the most terrible blow.

Source: The Last Castle (1966), Chapter 2, section 1