Most people equate the term "memory" with what is more accurately termed episodic memory - little movies in your head. Most people can't remember when "Christmas" was first defined for them, but they can rattle off many things about it - the date, the religious meaning, the corporate meaning, etc. This is semantic memory, and together they form your conscious explicit memory or declarative memory (there are differences between the two that are not relevant here). The brain often throws away the episode but keeps the concept, and that is what Paul is talking about here.
But there's more to it than that. Your unconscious implicit memory includes things you can't even articulate. That's the difference between the date of Christmas and how to ride a bike: the latter is nondeclarative. Learning a different way to ride a bike, or approach programming, is even more difficult than recomputing semantic memory.
You can (and should) read a new books and gain new episodes to base your facts and opinions on. Read diverse material with abandon. But when learning something nondeclarative, like a weight-lifting technique, it can be well worth seeking out an expert and learning it right the first time. With nondeclarative memory, what you don't know can hurt you.
For more on the science and classification of memory, the Wikipedia page is as good a starting place as any.
But there's more to it than that. Your unconscious implicit memory includes things you can't even articulate. That's the difference between the date of Christmas and how to ride a bike: the latter is nondeclarative. Learning a different way to ride a bike, or approach programming, is even more difficult than recomputing semantic memory.
You can (and should) read a new books and gain new episodes to base your facts and opinions on. Read diverse material with abandon. But when learning something nondeclarative, like a weight-lifting technique, it can be well worth seeking out an expert and learning it right the first time. With nondeclarative memory, what you don't know can hurt you.
For more on the science and classification of memory, the Wikipedia page is as good a starting place as any.
[0] http://en.wikipedia.org/wiki/Memory