 Empirical things are complexes of space-time with their qualities, and it is now my duty to attempt to show how the different orders of empirical existence are related to each other… [T]he nature of mind and its relation to body is a simpler problem in itself than the relation of lower qualities of existence to their inferior basis; and for myself it has afforded the clue to the interpretation of the lower levels of existence. (Alexander 1920ii: 3)