 It is worth noting that, in a letter of 1869, Wright used the term consilience to explain the advantages of positivism over the “older  philosophy.”[10]  Positivism, he said, is a system of “universal methods, hypotheses, and principles” founded on the sciences. It is not a universal science itself but must be “coextensive with actual knowledge, and exhibit the consilience of the sciences” (L, 141). Consilience was a term used by William Whewell in 1858 to describe the coherence and mutual consistency of different scientific disciplines as they develop. This coherence, for Whewell, was a test of the truth of the  sciences.[11]