Ralph Waldo Trine (9 September 1866 – 22 February 1958) was an American New Thought writer, philosopher and animal welfare activist.

He studied history and political science at Johns Hopkins University and obtained his A.M. from Knox College in 1893.

[5] Trine authored In Tune with the Infinite which has remained the most popular publication in the New Thought movement.

[2] Unlike most other New Thought writers, Trine did not resort to mental money making advice and has been described as "one of the rare purists whose books were guileless optimism".

[9] His book Every Living Creature called for kindness to animals and advocated a vegetarian diet.