 In other words, the noumenal “backing” of the phenomenal is nothing but the sum total of actual and possible human experience, which Sprigge considers, in terms going back to Bradley, a “concrete universal”. One could argue that this confused the sum total of experience or thought about reality with reality itself, but Sprigge rejects that kind of distinction from the beginning of his argument; basically, he holds all knowledge to be knowledge by acquaintance, and what we have when we subsume any experience under a concept or universal is an immediate relation to part of a concrete universal—so all of reality is itself mental in nature.