When Darwin completed his work, "On the origin of species", his publisher (Murray) urged him to add just three words, "by the Creator" to the final sentence. This, he said, would avoid all dispute and opposition to the book. Darwin refused. In his observations, he saw no evidence for the hand of the Creator.

Possibly another observer (such as Darwin's nemesis, Fitzroy) might have made the same observations, and tacked the last remark on. However, this would be an assumption, based on the observer's own faith, rather than an observation.

(The opposite, that Darwin's omission of the remark was also an assumption, can be argued. However, Darwin had previously been trained for a position in the Anglican clergy, and might have been expected to assume the presence of the Creator's hand. Finding no direct evidence for one, he changed his views.)