There have been times when the goal of scientific endeavor was to study the perceptual side of things. We can indeed fix the date of the change from the study of the perceptual side to the study of the functional side with great accuracy. It lies between Kepler and Newton.
Astronomy was originally a science of the perceptual side; it was a matter of finding the design behind the bewildering multitude of stars, a design ordained by God that made it possible for them to move in perfect harmony: on his search for the harmony Kepler found the laws governing the planetary motions. Newton on the other hand we find completely immersed in the functional side of the starry sky, as he formulates the laws of gravity.
Kepler was looking for a design — Newton was looking for a cause for the same phenomenon.
What had happened to cause this revolution? Something fundamentally shattering had happened — God had left the universe.
During the whole of the Middle Ages, God resided over an unshakeable celestial vault, with the fixed stars wielded to its surface, while the planets moved freely in space. Above in Heaven was the kingdom of God where He resided in unimaginable splendor, surrounded by saints and archangels.
Then Giordano Bruno broke the celestial vault and opened a view into infinite space, where the fixed stars also hover in space like luminous islands.
God, who until recently had been enthroned in Heaven, had become invisible. He had left the universe as when we left the room with the bell and closed the door behind us.
In the same way as we leave the bell behind us as a meaningless blob of matter, he had left the stars, that had until then obeyed his will, as accidental accumulations of mass, moving aimlessly around. The design of the world had broken down. Looking for it had become meaningless.
Giordano Bruno had to atone for his blasphemous deed in the year 1600 when he was burned at the stake in Rome. But his deed could not be undone. God himself had left the world.
The consequence of this was that scientists began to deal with the world in the way a deaf person deals with a street organ. The turning of the roller, the vibration of the tongues and the aerial waves, these things he can establish — but the tune stays hidden from him.
JAKOB VON UEXKÜLL, “The new concept of Umwelt: A link between science and the humanities,” Semiotica 134(1/4): 111-123