The Great Chain theorists, beginning as early as Leibniz, began to realize that the Great Chain could best be understood as a holarchy that is not given all at once, but rather unfolds over enormous stretches of historical and geographical time—starting with matter, then the emergence of sensation in life forms, then perception, then impulse, then image, and so on. And thus, about a century before Darwin, it was widely accepted in educated circles that the Great Chain had actually unfolded or developed over vast time. And—this was crucial—since the Great Chain contained no "gaps" or holes (because the plenitude of Spirit fills all empty spaces), the research agenda was to find any "missing links" in evolution.
Ken Wilber, A Brief History of Everything
