Lost

Maxwell (Newton's intellectual heir)  died the year Einstein was born. The latter
never learnt of Maxwell's work in a school setting because he studied in Germany;
he was self-taught on the subject.

In his own work, Einstein considers the quantum of light - the photon -
to be massless in and of itself. E = mc^2 gives the loss of energy and hence mass
of the emitting body,and similarly the increase in energy and hence mass of the
receiving body. The photon itself is zero, and constitutes a gauge value in quantum
mechanics.

Interestingly, this is not the case in high energy calculations (ie for a cyclotron).

Can't help but fear  translation difficulties might be at the heart of some
conumdrums in physics, but who is to tell?