No matter how much progress one makes, there is always the thrill of just beginning.
Robert H. GoddardHow many more years I shall be able to work on the problem I do not know; I hope, as long as I live. There can be no thought of finishing, for 'aiming at the stars' both literally and figuratively, is a problem to occupy generations, so that no matter how much progress one makes, there is always the thrill of just beginning.
Robert H. GoddardIt is not a simple matter to differentiate unsuccessful from successful experiments. . . .[Most] work that is finally successful is the result of a series of unsuccessful tests in which difficulties are gradually eliminated.
Robert H. Goddard