Men will always be making mistakes as long as they are striving after something. During such a long and difficult struggle the researcher might be tempted again and again to abandon his efforts as vain and fruitless, except that every now and then a light strikes across his path which furnishes him with irrefutable proof that, after all his mistakes in taking one by-path after another, he has at least made one step forward towards the discovery of the truth that he is seeking. The steadfast pursuance of one aim and purpose is indispensable to the researcher and that aim will always light his way, even though sometimes it may be dimmed by initial failures.

Max Planck

1919 Nobel Prize acceptance speech