Here's a quote from James' Pragmatism and Common Sense lectures that expresses the idea: Our minds thus grow in spots; and like grease-spots, the spots spread.

Here's a quote from James' Pragmatism and Common Sense lectures that expresses the idea: Our minds thus grow in spots; and like grease-spots, the spots spread. But we let them spread as little as possible: we keep unaltered as much of our old knowledge, as many of our old prejudices and beliefs, as we can. We patch and tinker more than we renew. The novelty soaks in; it stains the ancient mass; but it is also tinged by what absorbs it. [http://www.authorama.com/pragmatism-6.html http://www.authorama.com/pragmatism-6.html]