Full Idea
The determination of the boundaries of our reason can only take place in accordance with a priori grounds
Gist of Idea
The boundaries of reason can only be determined a priori
Source
Immanuel Kant (Critique of Pure Reason [1781], B786/A758)
Book Reference
Kant,Immanuel: 'Critique of Pure Reason', ed/tr. Guyer,P /Wood,A W [CUO 1998], p.653
A Reaction
I suspect that this is right, and is a truth of huge importance for philosophy. If we experience limitations in our reason (a not unusual experience!) this could never show that the boundary was necessary. This supports a minimal rationalism.