Kant, Immanuel - Critique of Pure Reason - Inner speech
Type of Spiritual Experience
Kany posited the existence of 'noumena' inner thoughts that do not come from the 5 senses but appear from other sources. Here is part of te very very long discussion he wrote on noumena
A description of the experience
Critique of Pure Reason – Transcendental Doctrine of Elements: Transcendental Logic
…… this kind of intuition [perception] does not embrace all things, but only objects of our senses; …, consequently, its objective validity is limited, and room is left for some other kind of intuition, and so also for things as objects of it.
But in that case the concept of a noumenon is problematic, that is, it is then the representation of a thing of which we can neither say that it is possible nor that it is impossible. For we know of no other kind of intuition but our sensible one, or of any kind of concept but of our categories; yet neither of them is applicable to any extrasensible object.
[but unless we admit of noumena] we cannot extend in a positive way the field of the objects of our thought beyond the conditions of our sensibility, or assume that besides appearances there exist also objects of pure thought, that is, noumena, simply because these objects do not possess any positive meaning that could be pointed out.