 Criticisms that quickly developed over the overt intentionality embedded in such passages, however, led Darwin to revise the argument in editions beginning with the third edition of 1861. From this point onward he explicitly downplayed the intentional and teleological language of the first two editions, denying that his appeals to the selective role of “nature” were anything more than a literary figure, and he moved decisively in the direction of defining natural selection as the description of the action of natural laws working upon organisms rather than as an efficient or final cause of life. He also regrets in his Correspondence his mistake in not utilizing the designation “natural preservation” rather than “natural selection” to characterize his principle (letter to Lyell 28 September 1860,  Burkhardt et al. 1993 8: 397; also see  Darwin Correspondence Project in Other Internet Resources).  The adoption in the fifth edition of 1869 of contemporary Herbert Spencer’s designator, “survival of the fittest” (Spencer 1864: 444–445; Origin 1869: 72), as a synonym for “natural selection”, further emphasized this shift of meaning away from the concept that can be extracted from the early texts and drafts. Thus the formulations of the principle in the final statements of the late 1860s and early 70s underlie the tradition of later “mechanistic” and non-teleological understandings of natural selection, a reading developed by his disciples who, in the words of David Depew, “had little use for either his natural theodicy or his image of a benignly scrutinizing selection” (Depew 2008: 253).