Learning ability determines percentage of skill proficiencies you gain from inspirationals.
If you study same inspirationals repeatedly, percentage of Learning ability will decrease then to converge 0%.
This is to prevent people from studying many inspirationals that are the same, and thus force them to use different kinds for best return.
If your Learning ability reaches a point that you find unworkable with, then you can click the “Reset” button next to it.
This will clear all currently accumulated proficiency points and reset the Learning ability back to 100%.
Don't worry it will not remove any skill levels...