
“One touch of nature makes the whole world kin.”
The Cruise of the Corwin http://www.sierraclub.org/john_muir_exhibit/writings/cruise_of_the_corwin/default.aspx (1917), chapter 3: Siberian Adventures <!-- Terry Gifford, LLO, page 738 -->
(Echoing William Shakespeare, Troilus and Cressida, iii, 3: "One touch of nature makes the whole world kin.")
1910s
Variant: One touch of nature makes all the world kin.
Source: Our National Parks