It 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.
![It 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](http://cdn.quoteddaily.com/images/robert-h-goddard/it-is-not-a-simple-matter-to-differentiate-unsuccessful-from-successful-experiments---most-work-that-is-finally-successful.jpg)
It 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.