pect themselves and posterity in the
employment of their time. What would posterity think of us if we had
nothing to transmit to it save a complete insectology, an immense
history of microscopic animals? No--to the great geniuses great objects,
little objects to the little geniuses" (Sec. 54).

Diderot, while thus warning inquirers against danger on one side, was
alive to the advantages of stubborn and unlimited experiment on the
other. "When you have formed in your mind," he says, "one of those
systems which require to be verified by experience, you ought neither to
cling to it obstinately nor abandon it lightly. People sometimes think
their conjectures false, when they have not taken the proper measures to
find them true. Obstinacy, even, has fewer drawbacks than the opposite
excess. By multiplying experiments, if you do not find what you want, it
may happen that you will come on something better. _Never is time
employed in interrogating nature entirely lost_" (Sec. 42). The reader will
not fail to observe that this maxim is limited by the condition of
verifiableness. Of any system that could not be verified by experience
Diderot would have disdained to speak in connection with the
interpretation of nature.

This, of course, did not prevent him from hypothesis and prophecy which
he himself had not the means of justifying. For example, he said that
just as in mathematics, by examining all properties of a curve we find
that they are one and the same property presented under different faces,
so in nature when experimental physics are more advanced, people will
recognise that all the phenomena, whether of weight, or elasticity, or
magnetism, or electricity, are only different sides of the same
affection (Sec. 44). But he was content to leave it to posterity, and to
build no fabric on unproved propositions.

In the same scientific spirit he penetrated the hollowness of every
system dealing with Final Causes:

"The physicist, whose profession is to instruct and not to edify,
will abandon the _Why_, and will busy himself only with the
_How_.... How many absurd ideas, false suppositions, chimerical
notions in those hymns which some rash defenders of final causes
have dared to compose in honour of the Creator? Instead of sharing
the transports of admiration of the prophet, and crying out at the
sight of the unnumbered stars that light up the midnight sky, _The
heavens declare the glo