One of the best ways of understanding what insight means is to look at certain theories, especially those which deal with universal order. The word “theory” comes from the same root as the word theater. It means to look, to make a spectacle. You could say a theory was originally a way of looking at the world. The idea that theories could be proposed and discussed freely began with the ancient Greeks. Before that time, theories of universal order were incorporated into religious systems which were not freely discussed or questioned. The Greeks proposed and discussed, with great passion, a wide range of fundamental theories. In these discussions a certain notion of universal order developed which was carried forward into medieval Europe.
It was believed that heavenly matter, being most perfect, would move in perfect orbits, and the most perfect orbit was considered to be a circle. Actual observations showed, even to the ancient Greeks, that the planets were not moving in circular orbits, but this did not prevent them from holding onto the idea of perfection. Rather, they accommodated the idea by saying they are circles superimposed on circles called epicycles. By adding enough epicycles you could still account for the heavenly motions and retain the notion of circularity. In a deeper sense however, it was an evasion of afundamental challenge.
One reason why observation didn’t lead the Greeks to question increasing perfection was their belief that reason was of highest value, while the senses were regarded as unreliable and deceptive, which they often are. The very idea of universal order also generates strong feelings and any challenge may be sensed as a threat to the whole of existence. Therefore, there is a great reluctance to question notions of universal order.
Toward the end of the Middle Ages Roger Bacon suggested that observation and experience could criticize ideas that appeared to be reasonable. This was revolutionary and the beginning of the scientific approach. It made it possible to correct the Greek bias toward reason and to limit the extreme power of knowledge, which at that time was so great that nothing could really challenge it.
As this approach began to take hold, observation and experience accumulated showing there was nothing particularly perfect about heavenly matter. In general, people were not aware of how this knowledge was a fundamental challenge to prevailing ideas about the nature of matter. Newton sensed this challenge and was the first to face it fully.
According to the story, he saw an apple falling, and by implication must have asked himself, “Why isn’t the moon falling?” And his answer was very simple, “The moon is falling,”and, indeed, because all matter is basically the same, every such free body is falling toward every other, which implies a universal force of gravitation. This discovery was a flash of perception, an insight.