Seeing the frightening nature of a condition where he can hold onto nothing and rely on nothing, man builds up concepts of the world he finds himself in.
Then in the course of his development, through upbringing and education, a person learns to respond more to those concepts that he has acquired, than to mere stimulation of the senses and fleeting desires, although for long, usually his concepts will many times fail him, or his life-situation, so that he will be forced to narrow down the sphere of conceptualisation and to draw a veil over that part of reality which appears to him as yet utterly unmanageable.
Taking as an example a person growing up in an abusive family atmosphere. Such person is not likely to have much interest in the world at large. All (or most) of his mental processing (conceptualizing) will be occupied with figuring out his family situation. And further on, to the degree his concepts fail him in managing his life situation, usually he will seek consolidation in destructive activities like drinking and drugs, in order to reduce the sphere of experienced reality even further.
A person coming into contact with meditation, learns at first to reduce the sphere of experienced reality by himself…which gives him a tool to overcome those most coarse of destructive activities. Becoming thus more self dependent and more capable of choosing the amount of information to enter his sphere of experience, a person also learns to build up better concepts regarding the world that enters his sphere of experience. With that, he becomes more confident in broadening his world.
Building thus concepts about the world, consciousness gets trained to cognise and processes only that part of the world, which relate to a particular line of thought. A Buddhist training in his path, deliberately chooses as his main line of thought the four noble truth. Nevertheless growing up in the world, various types of concepts related to that world will equally enter into the equation. And Buddhist or Non-Buddhist having a main line of thought or not, it is the nature of man to learn and to broaden his conception of the world. In Buddhist meditative traditions, traditionally there is a path of gradual training, moving from the sense-sphere world to the subtler fine-material-sphere on towards the sphere of formless ideas, which for a Buddhist each will have to be put subservient to his main idea of the four noble truth. Thus seeking no consolidation in any sphere if it will be a cause for further suffering (like when a person in order to improve the supporting conditions for his meditation is doing various unwholesome deeds in the sense-sphere world).
It is the lack of having a true seed philosophical line of thought (as for a buddhist are the 4 noble truth), to which any other type of thought is subservient, that is at the root of all confusion.
