 Whitehead was dissatisfied with Hume’s reduction of perception to sense perception because, as Hume discovered, pure sense perception reveals a succession of spatial patterns of impressions of color, sound, smell, etc. (a procession of forms of sense data), but it does not reveal any causal relatedness to interpret it (any form of process to render it intelligible). In fact, all “relatedness of nature”, and not only its causal relatedness, was “demolished by Hume’s youthful skepticism” (1922 [2004: 13]) and conceived as the outcome of mere psychological association. Whitehead wrote: