Jean-Paul Sartre: existentialist philosopher, playwright, novelist, screenwriter, political activist, biographer, and literary critic. One of the leading figures in 20th century French philosophy, existentialism, and Marxism, his work continues to influence fields such as Marxist philosophy, sociology, and literary studies. He had a long relationship with the author and social theorist, Simone de Beauvoir. He was awarded the 1964 Nobel Prize in Literature but refused the honour. Together, Sartre and de Beauvoir challenged the cultural and social assumptions and expectations of their upbringings, which they considered bourgeois, in both lifestyle and thought. There's a good summary of his philosophy and thought here.
"If you are lonely when you're alone, you are in bad company."
"Generosity is nothing else than a craze to possess. All which I abandon, all which I give, I enjoy in a higher manner through the fact that I give it away. To give is to enjoy possessively the object which one gives."
"I do not believe in God; his existence has been disproved by Science. But in the concentration camp, I learned to believe in men."
"I am no longer sure of anything. If I satiate my desires, I sin but I deliver myself from them; if I refuse to satisfy them, they infect the whole soul."
"If I became a philosopher, if I have so keenly sought this fame for which I'm still waiting, it's all been to seduce women basically."
"It disturbs me no more to find men base, unjust, or selfish than to see apes mischievous, wolves savage, or the vulture ravenous."
"There are two types of poor people, those who are poor together and those who are poor alone. The first are the true poor, the others are rich people out of luck."
"There is only one day left, always starting over: it is given to us at dawn and taken away from us at dusk."
"We do not judge the people we love."
"Words are loaded pistols."