To live among friends is the primary essential of happiness.

William Thomson, Lord Kelvin (1824–1907) Scottish physicist

Lord Kelvin’s Replies to Addresses given on the Celebration of the Jubilee of his Professorship (15-17 Jun 1896)
    (Source)

Quoted in G. Fitzgerald, Lord Kelvin, Professor of Natural Philosophy in the University of Glasgow 1846-1899 (1899)