Clarity Of The Bargain
Of course, that was a capacity that was never reached by the average human. But when it came to the mages, sorcerers, priests, and many other powerful people of Lucius's past world, that limit was not unreachable.
Usually, how the brain worked was that it would push out or delete older and unused memories to make room for new ones. This way it would never run out of space as it would keep on cleaning the storage.
But this was a problem for the stronger mages.
To mages, their memory was one of the most important things to them. All of the things that they learned, whether it be magic theory, spell matrices, spell forms, runes, scripts, curses, and many more things, they all needed a lot of memory.
While it was not often, there were actually mages that ended up reaching the limits of the human brain. Of course, over the years there were many solutions to this that had been researched by the scholars.