The above quote comes from "An Outline of Intellectual Rubbish". In it he attempts to find the rationality of man, and only succeeds in finding the folly in everything from the ancient Greeks, religion, politics, secularism, pacifists, aggressive people, and really just about anyone. It is home to many, many good quotes as well. I'm not kidding, this essay is great.
Among some of his gems in the essay is a part about spending time with people who disagree with you. Honestly, so often I forget that people have different opinions then myself. Naturally, I want to stay away from "toxic" people whose opinions just seem to hold me back. These people can be a blessing though. Contrary to what I like to believe sometimes, I am not the greatest thing in the world, or universe, or even the greatest thing in this state. I have flaws, and when others are used correctly, they can help point out those flaws. Other opinions show you that world is dynamic, it is change. Mostly though, it's what reminds that the world is not a figment of my own imagination.
Besides writing essays, he was also a mathematician. He wrote some classics on logic in the early 1900's, including Principia Mathematica, in which he and Alfred North Whitehead attempted to describe a set of mathematic truths in which all of math could be proven. Kurt Godel later prove with his incompleteness therom that this was not possible.
Here is his essay
Here is Principia Mathematica
And here is a dog trying to stay awake