Definition
Forbidden knowledge is any information, skill, or understanding that your fictional world considers too dangerous, corrupting, or destabilizing to be freely known. This can include dark magic spells, cosmic truths that shatter sanity, historical secrets that would topple governments, or scientific discoveries with catastrophic potential. The 'forbidden' label can come from religious institutions, magical authorities, or the inherent nature of the knowledge itself. The narrative power lies in the temptation to learn it anyway.
Why It Matters
Forbidden knowledge creates instant tension the moment a character encounters it. Do they pursue it and risk the consequences, or walk away and lose a potential advantage? It also lets you explore themes of power, responsibility, and the ethics of discovery. Some of fiction's most compelling moments come from characters who learn something they can't unlearn.
Types of Forbidden Knowledge
Famous Examples
The entire Lovecraft mythos revolves around forbidden knowledge; characters who learn too much about the cosmos lose their sanity.
The secrets of the Others, the true history of the Long Night, and various characters' parentage are all forms of knowledge that people kill and die for.
The Chandrian's names are forbidden knowledge; even speaking about them draws dangerous attention.
Common Mistakes
Establish why the knowledge is forbidden. Is it because it corrupts? Because it enables mass destruction? Because it threatens the powerful? The reason shapes how characters interact with it.
If you label something forbidden and then let characters use it freely, you undermine the entire concept. Even partial consequences (a small corruption, a political target on their back) maintain credibility.
The difficulty of accessing forbidden knowledge should match its danger. If it could destroy the world, it shouldn't be in a book on the regular library shelf.
Try It Yourself
Create a piece of forbidden knowledge for your world. Write a one-paragraph description of what the knowledge is, who forbade it and why, and what happens to someone who learns it. Then write a short scene (10 sentences max) where a character discovers a fragment of this knowledge and must decide whether to pursue it further. Focus on the internal conflict.
Map Your World's Secrets
Use the Worldbuilding tools to track what's known, what's hidden, and who's keeping secrets, so your forbidden knowledge stays consistent across your manuscript.