"Most authors say it in an endevour to discover the laws according to which the Creator has willed to produce organized beings - But what empty high-sounding sentences are these - it does not mean order in time of creation, nor propinquity to any one type, as man. - in fact it just means nothing - According to my opinion, (which I give every one leave to hoot at, like I should have, six years since, hooted at them, for holding like views) classification consist in grouping beings according to their actual relationship, ie their consanguinity, or descent from common stocks " Charles Darwin, letter to George Robert Waterhouse, 26 July 1843
Here Darwin is rejecting supernatural explanations for natural ones. Why? Supernatural explanations are not explanations at all. Unless we understand the substance of supernatural actions, we aren't explaining anything - what does it mean to say "it just happened"?