Pure being, which has nothing of nonbeing in itself, is in such wise eternally infinite that no nonbeing is before it or after it, and it contains in itself all that is and can be. This being is all that it is in the highest measure of being, or more correctly, it is measureless (it is very measure by which all else is to be measured) -- it is pure act. In it nothing is shut, nothing remains unfolded; it is rather in absolute openness, illumined in itself and through itself; that is, it is light itself -- it is pure spirit.
If anything is other than pure spirit, it can be only thruogh pure spirit. Whatever is other than pure being can be set off from it only by having bounds [Einschrankung], by being something yet not everything, by being yet without being in full measure -- by being as an analogue of pure being, I mean by being like pure being yet more unlike it.
[Edith Stein, Potency and Act, Walter Redmond, tr., ICS Publications (Washington, DC: 2009), p. 413.]