“A manuscript I wrote on January 14, 1918 … and deposited in a friend’s safe … speculated as to the last migration of the human race, as consisting of a number of expeditions sent out into the regions of thickly distributed stars, taking in a condensed form all the knowledge of the race, using either atomic energy or hydrogen, oxygen and solar energy… [It] was contained in an inner envelope which suggested that the writing inside should be read only by an optimist.”

— Robert Goddard, “Material for an Autobiography,” (1927), available in Pendray, G. E. and Goddard, E. C. (Eds.), The Papers of Robert H. Goddard (New York: McGraw Hill, 1970).