Be the change you wish to see in the world.
The real story
Gandhi did not say this. The Gandhi Institute for Nonviolence has stated there is "no reliable documentary evidence" for Gandhi saying this exact phrase. Gandhi did write a thematically related passage in 1913 — "If we could change ourselves, the tendencies in the world would also change" — but it is longer and less pithy than the popular version. The concise modern formulation "be the change you want to see happen" was published in 1974 by educator Arleen Lorrance in a chapter titled "The Love Project" (in Kellough, ed., "Developing Priorities and a Style"). Quote Investigator credits Lorrance with the expression.