THE PRINCIPLE OF HOPE

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time technology was still connected with handicrafts, and almost only in Agricola (De re metallica, 1530) was practical activity accorded the same status as theory.
There is also something else which, for their part, kept the majority of inventors in those days aloof from mathematical and mechanical knowledge. For the magic natural
background had still by no means collapsed for them; the world of Paracelsus took root and survived for a long time precisely in technological books. Above all in
those dealing with mining; the earth­spirit or a ghostly life in the depths had a naive effect on the technologists at that time, just as it stirred the poets and the
philosophers of nature sentimentally again so much later, in Romanticism. The gases in the air were demons who were after the miner's blood, the rising waters from the
depths contained a living water­spirit, whereas the falling waters which have to be raised were therefore regarded as dead waters, in short, even in this direction
technology, and not just alchemy, lived in a qualitatively magical and not in a quantitatively mechanical world. Almost solely in Italy, as the most advanced capitalist
country at that time, was invention linked with early calculation. Around 1470 the engineer Valturio sketched a car, called a ‘storm carriage’, with windmill sails at the
side, the drive was transmitted to the wheels of the carriage by means of cogwheels, and the sketch was worked out mathematically. And when Brunelleschi put
together the machines for building his dome of Florence cathedral himself, they were combined levers and inclined planes in a mathematically considered design. And as
far as the bold technologist Leonardo da Vinci is concerned, he is the first purely immanent inventor and scientist whatsoever, working on the basis of causality
(‘necessity’). Keen observation and careful calculation assisted his varied plans; occasionally with the errors of the pioneer, but without any dilettantism. Thus he
designed the first parachute, the first turbine (preserved as a sketch: ‘Propeller in a canal’), and the first flyover system (likewise preserved as a sketch: ‘Design for
streets lying above one another’). He studied the flight of birds in order to realize the human dream of flight, the oldest of all the technological wishful images: ‘I intend to
make the big artificial bird take his first flight; it will fill the universe with amazement, and all works with its fame; eternal glory will be accorded to the nest where it was
born.’ The bird was to rise in Florence, but it never got beyond a plan, and Icarus did not even fall, so little did he rise from the ground. And of course the mathematical
mechanics on which Leonardo wanted to base his inventions was only developed after his death. And furthermore even Leonardo, despite the mathematically
constructive instinct which so characteristically distinguishes him, did not wholly emerge from the organic view of nature of the Renaissance. On the contrary: