Louis de Broglie

"It seems a little paradoxical to construct a configuration space with the coordinates of points which do not exist."

"The history of science shows that the progress of science has constantly been hampered by the tyrannical influence of certain conceptions that finally came to be considered as dogma. For this reason, it is proper to submit periodically to a very searching examination, principles that we have come to assume without any more discussion."

"Two seemingly incompatible conceptions can each represent an aspect of the truth … They may serve in turn to represent the facts without ever entering into direct conflict."

"The actual state of our knowledge is always provisional and … there must be, beyond what is actually known, immense new regions to discover."

"Admettant que la particule possède une vibration interne qui permet de l'assimiler à une petite horloge, je supposais que cette horloge se déplaçait dans son onde de façon que sa vibration interne reste constamment en phase avec celle de l'onde : c'est le postulat de l'accord des phases."