The human is simply a "creature of habit"; once learnt, learnt forever, he often thinks. For him it is hard to understand that what he has learnt today is only a part of the whole. Not that someone is withholding the rest from him, but in accordance with his momentary situation he is not capable of seeing further, of understanding more, of perceiving more. This momentary understanding serves for nothing else but to lead him to the next and the following step, to further discoveries. When the human isolates what he has already learnt as a rigid, fixed realisation or even as unalterable fact, he thereby blocks himself off in his own further development and makes no headway until something happens which helps him to look differently at the thing or himself or the position in which he is stuck, and the reason why he is making no headway.