Defining terms :
Concentration= focussed awareness.
Memories = changes in perception. Occur over and are influenced by time, the fourth dimension.
The arrow in the diagram below shows increasing speed of concentration
no concentration increasing speed of perception
However , although concentration increases it is never as fast as ‘being there (Enlightenment)’
Perception will always be happening as concentration increases and awareness changes. As time (and so memory) is involved, awareness always results in an inside and outside as the yin and yang halves of the process occur between the object of concentration and the subject i.e. we always have a sense of movement and change in awareness/identity through using concentration.
So concentration & memory (time) stops us from simply ‘being’ where an inside and outside would not exist, environments would not be created (through the process of perception) and there would be simply NOW.
Perhaps Buddhi, which does not have memory, is free from environments, awareness and perception. Here there is also no ‘inside and outside’.