Assuming that the particle has an internal vibration which allows to assimilate it to a small clock, I supposed that the clock was traveling with the wave in such a way that its internal vibration remained constantly in phase with the wave's : this is the phase matching postulate.

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.

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.