It is difficult to say what is impossible.

How 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.

The dreams of yesterday are the hopes of today and the reality of tomorrow.

The reason many people fail is not for lack of vision but for lack of resolve and resolve is born out of counting the cost.

It is difficult to say what is impossible

No matter how much progress one makes, there is always the thrill of just beginning.

Set goals, challenge yourself, and achieve them. Live a healthy life...and make every moment count. Rise above the obstacles, and focus on the positive.

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.

Every vision is a joke until the first man accomplishes it; once realized, it becomes commonplace.

The only barrier to human development is ignorance, and this is not insurmountable.