“To live among friends is the primary essential of happiness.”
Lord Kelvin’s Replies to Addresses given on the Celebration of the Jubilee of his Professorship (June 15-17, 1896). Quoted in Lord Kelvin, Professor of Natural Philosophy in the University of Glasgow 1846-1899 (1899) by George F. Fitzgerald http://historical.library.cornell.edu/cgi-bin/cul.math/docviewer?did=03620002