• The doctrine of evolution implies the passage from the most organised to the least organised, or, in other terms, from the most general to the most special. Roughly, we say that there is a gradual 'adding on' of the more and more special, a continual adding on of new organisations. But this 'adding on' is at the same time a 'keeping down'. The higher nervous arrangements evolved out of the lower keep down those lower, just as a government evolved out of a nation controls as well as directs that nation.

    John Hughlings Jackson (1931). “Selected Writings of John Hughlings Jackson: Evaluation and dissolution of the nervous system. Speech. Various papers, addresses and lectures”