“If I am an agnostic, Calyxa, it’s because I'm also a realist.”

Why I Am An Agnostic (1929)
Context: I am an agnostic as to the question of God. I think that it is impossible for the human mind to believe in an object or thing unless it can form a mental picture of such object or thing. Since man ceased to worship openly an anthropomorphic God and talked vaguely and not intelligently about some force in the universe, higher than man, that is responsible for the existence of man and the universe, he cannot be said to believe in God. One cannot believe in a force excepting as a force that pervades matter and is not an individual entity. To believe in a thing, an image of the thing must be stamped on the mind. If one is asked if he believes in such an animal as a camel, there immediately arises in his mind an image of the camel. This image has come from experience or knowledge of the animal gathered in some way or other. No such image comes, or can come, with the idea of a God who is described as a force.

"Da Vinci Code Author Dan Brown Says He Has Abandoned Christianity, but Is Not an Atheist" The Christian Post (24 Oct 2017) https://www.christianpost.com/news/da-vinci-code-author-dan-brown-says-he-has-abandoned-christianity-but-is-not-an-atheist-204122

Larry King Live interview (2010)
Context: I don't hate America. I love America. I want it to be better. The only way we can get it to be better is to realistically criticize what's wrong with it. That's not what the Republicans do. … I don't want to be a pessimist. I'm a realist. One man's realist is another man's pessimist. But, no, I'm not like Mitt Romney, whose book is called No Apology, the Case for American Greatness. Really? Always waving the big foam number one finger; we're not number one in most things. We're number one in military. We're number one in money. We're number one in fat toddlers, meth labs, and people we send to prison. We're not number one in literacy, money spent on education. We're not even number one in social mobility. Social mobility means basically the American dream, the ability of one generation to do better than the next. We're tenth. That's like Sweden coming tenth in Swedish meatballs.

As quoted in a eulogy for Darrow by Emanuel Haldeman-Julius (1938)

Surefish interview (2002)
Context: I'm caught between the words 'atheistic' and 'agnostic'. I've got no evidence whatever for believing in a God. But I know that all the things I do know are very small compared with the things that I don't know. So maybe there is a God out there. All I know is that if there is, he hasn't shown himself on earth.
But going further than that, I would say that those people who claim that they do know that there is a God have found this claim of theirs the most wonderful excuse for behaving extremely badly. So belief in a God does not seem to me to result automatically in behaving very well.

as quoted by Olgierd Budrewicz in The melting-pot revisited: twenty well-known Americans of Polish background http://books.google.com/books?ei=jntPUNaTMafZ0QHMloGQBQ&id=pc51AAAAMAAJ&dq=Olgierd+Budrewicz%7C&q=Sometimes+I+muse#search_anchor, publish by Interpress, page 36, 1977.

Source: Cat's Eye

Utilitarianism and Vegetarianism, Philosophy & Public Affairs, 9(4): 325 (1980).