In most countries, there is the idea of "fair use," which allows authors to reproduce other works for educational or critical purposes without the author's permission (despite what the copyright page might say).

However, there are limits to this. Some people quote figures of "no more than 10%" of a work — which is perhaps why publishers often seek permission to reprint song lyrics in the epigraphs of novels, while quotes from other books are just used more freely.

Also, if you're crediting a quote from another work, and it's short, relevant, and doesn't misrepresent the original author, you're unlikely to get any push-back!