The only thing we can say is that we observe phenomena. We have some idea of the world as we perceive it. How this representation is constructed, we will have to suggest. This principle will be called '''"The phenomenological cage principle"'''. Philosophers had tried for centuries since Hume and Kant to describe the inner mechanisms that constructed our perception, but no final solution was achieved. So to solve this problem I will use ideas that were taken from neurophysiology, and may comply to the philosophic literature.