A book can be banned by people who thereby teach others that it contains something powerful.

Suppression advertises. The act of forbidding a text announces that someone powerful believed it could do something, and that belief transfers straight to the reader, who now approaches with an appetite they would not otherwise have had. Attempts to shrink attention frequently enlarge it.

You can use this in both directions. Notice when your interest in something is really interest in the fact that someone tried to hide it, and check whether the thing itself holds up. And when you want to reduce the reach of something, consider that public objection may be the loudest recommendation you could give it.