interval it must remain immovable, and the divers instants during which it
keeps in the same state can no longer be discriminated from one another;
we thus reach a conception of the discontinuous variation of time--the
atom of _time_."

I quote in conclusion, Poincaré's final remarks:

"The present state of the question is thus as follows: the old theories,
which hitherto seemed to account for all the known phenomena, have met
with an unexpected obstacle. Seemingly a modification becomes necessary. A
hypothesis has presented itself to M. Planck's mind, but so strange a one
that one is tempted to seek every means of escaping it; these means,
however, have been sought vainly. The new theory, however, raises a host
of difficulties, many of which are real and not simply illusions due to
the indolence of our minds, unwilling to change their modes of thought....

"Is discontinuity to reign through out the physical universe, and is its
triumph definitive? Or rather shall we find that it is but apparent and
hides a series of continuous processes?... To try to give an opinion just
now on these questions would only be to waste ink."

It only remains to call attention again to the fact that this conception
of the discontinuity of energy, the acceptance of which Poincaré says
would be "the most profound revolution that natural philosophy has
undergone since Newton" was suggested by the present writer fifteen years
ago. Its reception and serious consideration by one of the first
mathematical physicists of the world seems a sufficient justification of
its suggestion then as a legitimate scientific hypothesis.