Belief is mentioned later in the article, clarifying the meaning. But be assured: knowledge is only ever a form of belief. The laws of physics could change tomorrow (this is not precluded by any provable rule of existence). Really everything we know, we know inductively. (Mathematical knowledge is excluded from this obviously because of its weird, tautological nature--but within math, the discovery of non-Euclidean geometry is a good example of things that were thought to be necessarily true turning out to be merely axiomatic)
Another example of "knowledge" being used in the sense meant by the article is this:
"It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so." --Mark Twain
"Quotations on the internet are often misattributed." -- Abraham Lincoln
(The "what you know that ain't so" thing actually seems to have originated with Josh Billings. I don't think Mark Twain used it.)
But how would an individual know the difference between "knowledge" and "belief"?
Some say that knowledge is justified true belief[1], others disagree[2].
[1] https://en.wikipedia.org/wiki/Justified_true_belief#Justifie... [2] https://en.wikipedia.org/wiki/Gettier_problem
That's not knowledge - that's belief.
> Read books are far less valuable than unread ones.
Eh, I agree having books you can refer to is useful, but I would argue you can't really refer to them unless you've read them. If they're really worthwhile, you'll read them, learn something, and keep them for future reference, perhaps even future re-reading.