Respectfully Quoted: A Dictionary of Quotations. 1989.
John Fitzgerald Kennedy (191763)
In its [knowledges] light, we must think and act not only for the moment but for our time. I am reminded of the great French Marshal Lyautey, who once asked his gardener to plant a tree. The gardener objected that the tree was slow-growing and would not reach maturity for a hundred years. The Marshal replied, In that case, there is no time to lose, plant it this afternoon.
President JOHN F. KENNEDY, address at the University of California, Berkeley, California, March 23, 1962.Public Papers of the Presidents of the United States: John F. Kennedy, 1962, p. 266.
Kennedy used this story a number of times. The attribution to Marshal Lyautey is unverified.