Sforza in Milan in a state of dignified abstraction. His common-place
books are full of prophetic subtlety and ingenious anticipations of
the methods of the early aviators. Durer was his parallel and Roger
Bacon--whom the Franciscans silenced--of his kindred. Such a man again
in an earlier city was Hero of Alexandria, who knew of the power of
steam nineteen hundred years before it was first brought into use.
And earlier still was Archimedes of Syracuse, and still earlier the
legendary Daedalus of Cnossos. All up and down the record of history
whenever there was a little leisure from war and brutality the seekers
appeared. And half the alchemists were of their tribe.

When Roger Bacon blew up his first batch of gunpowder one might have
supposed that men would have gone at once to the explosive engine. But
they could see nothing of the sort. They were not yet beginning to think
of seeing things; their metallurgy was all too poor to make such
engines even had they thought of them. For a time they could not make
instruments sound enough to stand this new force even for so rough a
purpose as hurling a missile. Their first guns had barrels of coopered
timber, and the world waited for more than five hundred years before the
explosive engine came.

Even when the seekers found, it was at first a long journey before the
world could use their findings for any but the roughest, most obvious
purposes. If man in general was not still as absolutely blind to the
unconquered energies about him as his paleolithic precursor, he was at
best purblind.

Section 4

The latent energy of coal and the power of steam waited long on the