Early in life I became aware of something that I would now know philosophers call the internal and external worlds. It goes something like this:

The external world is a place where things happen beyond my control. Things are somewhat acting independently to each other. The internal world is different to the external world. The thoughts of the internal is different to the actions of the external world. They seem to separate worlds. My body interface to the external world is public. No one knows of my private thoughts of the internal world. These two worlds, the public and the private, never meet.

To me, this paradigm is problematic. It suggests that there is not one but two worlds. It also suggests that these worlds are unbridgeable and hence separate.