Tu n'avais oublié qu'un point:
C'était d'éclairer ta lanterne.[163]


The meeting together of the understanding and of facts is a discovery;
and discovery depends upon a faculty sung by poets, admired by mankind,
and too little noticed by logicians--genius. Genius has for its
characteristic a sudden illumination of the mind, a gratuitous gift and
one which cannot be purchased. But let us hasten to supply a necessary
explanation. Genius is a primitive fact, a gift; but the work of genius
has conditions, or rather a condition--labor. Labor does not replace
genius, but genius does not dispense with labor; nature only delivers up
her secrets to those who observe her with long patience. Newton was
asked one day how he had found out the system of the universe. He
replied with a sublime _naïveté_: "By thinking continually about it." He
so pointed out the condition of every great discovery; but he forgot the
cause--the peculiar nature of his own intellect. It was necessary to be
always pondering the motions of the stars; but it was necessary moreover
to be Isaac Newton. So many had thought on the subject, as long perhaps
as he, and had not made the discovery.

Labor, the condition of discoveries, should have as its effect to
recognize the methods really appropriate to the nature of the inquiries,
and to keep the mind well informed in existing science. In fact, every
scientific discovery supposes a series of previous discoveries which
have brought the mind to the point at which it is possible to see
something new. For this reason it is that a discovery often presents
itself to two or three minds at once, when there are found, at the same
epoch, two or three minds endowed with the same power. They see all