Leibniz

 
Matter/Materialism
Convinced of the earlier existence in the evolution of consciousness of archetypal matter or "Edenstuff," Barfield seeks to reconsider the distinction between matter and spirit that has proved so essential to the history of philosophy. He hopes to free our understanding of the nature of matter from the grip of current idolatry and convince us that the common sense view of matter we now assume is completely time-bound.

Insisting--in "Matter, Imagination and Spirit"--that we "begin by assuming straightaway not merely that matter is a form of arrested physical energy, but that Leibniz was right when he propounded that matter is coagulum spiritus--a kind of coagulation or concentration of spirit--that the material is formed from and within the immaterial rather as ice is formed from and within water" (RM 145), Barfield theorizes that the evolution of consciousness will produce, with the coming of final participation, the "spiritualization of matter" as the long-term result of an earlier "materialization of spirit" (SP 26).1
 

See in particular "Matter, Imagination, and Spirit" (RM 143-54) and "The Coming Trauma of Materialism" (RM 187-200).
1In History, Guilt, and Habit, Barfield shows that both materialist and idealist thinking have their disadvantages.
    One of the disadvantages of being an out-and-out materialist is that you can no longer use the word 'nature' with any consistency, because in your system it includes everything; just as one of the disadvantages of being an out-and-out idealist is that you can no longer use the word 'spirit' meaningfully, because in your system it includes everything. (HGH 5)
No doubt an awareness of this dilemma is what lead Barfield to espouse the position known as "objective idealism."