No man is justified in doing evil on the ground of expediency. He is bound to do all the good possible. Yet he must consider the question of expediency, in order that he may do all the good possible, for otherwise he will do none.Theodore Roosevelt (1858-1919) US President (1901-1909)
“Latitude and Longitude Among Reformers,” The Century (Jun 1900)
Collected in his volume of essays and addresses, The Strenuous Life (1900); the first sentence is most often quoted, and often cited under that book's name (not to be confused with its title essay). Full text.