ing and
convergence of _two_ factors--one internal (individual genius), the
other, external (the fortuitous occurrence).

It is impossible to determine all that invention owes to chance in this
sense. In primitive humanity its influence must have been enormous: the
use of fire, the manufacture of weapons, of utensils, the casting of
metals: all that came about through accidents as simple as, for example,
a tree falling across a stream suggesting the first idea of a bridge.

In historic times--and to keep merely to the modern period--the
collection of authentic facts would fill a large volume. Who does not
know of Newton's apple, Galileo's lamp, Galvani's frog? Huygens declared
that, were it not for an unforeseen combination of circumstances, the
invention of the telescope would require "a superhuman genius;" it is
known that we owe it to children who were playing with pieces of glass
in an optician's shop. Schoenbein discovered ozone, thanks to the
phosphorous odor of air traversed by electric sparks. The discoveries of
Grimaldi and of Fresnel in regard to interferences, those of Faraday, of
Arago, of Foucault, of Fraunhofer, of Kirchoff, and of hundreds of
others owed something to "fortune." It is said that the sight of a crab
suggested to Watt the idea of an ingenious machine. To chance, also,
many poets, novelists, dramatists, and artists have owed the best part
of their inspirations: literature and the arts abound in fictitious
characters whose real originals are known.

So much for the external, fortuitous factor; its role is clear. That of
the internal factor is less so. It is not at all apparent to the
ordinary mind, escaping the unreflecting. Yet it is extremely important.
The same fortuitous event passes by millions of men without exciting
anything. How many of Pisa's inhabitants had seen the lamp of their
cathedral before Galileo! He does not necessarily find who wants to
find. The happy chance comes only to those worthy of it. In order to
profit thereby, one must first possess the spirit of observation,
wide-awake attention, that isolates and fixates the accident; then, if
it is a matter of scientific or practical inventions, the penetration
that seizes upon relations and finds unforeseen resemblances; if it
concerns esthetic productions, the imagination that constructs,
organizes, gives life.

Without repeating an evident truism, although it is often misunderstood,
we ought to end by remarking that _chan