Knowledge Fragments are scarce items that can be found in various loot chests throughout the world, and can also be purchased from Pech.
Knowledge fragments can be distilled for 8 Cognitio essentia, used to craft Unknown Research, or used to gain (random) research points.
These research pages can be crafted with Knowledge Fragments. In older versions, they were the only way to learn certain research topics.
In your travels you might happen upon fragments of ancient and lost knowledge. On their own they are only worth a few research points when used but if you gather enough of them together, you might gain unique research that you can The fragments of knowledge can on occasion lead to a false theory, but this will be revealed when you attempt to research it. When this happens most of your knowledge fragments will be returned to you and it usually means you have exhausted all current avenues of research into lost knowledge.