The constant laws of nature that are the foundation of modern science and mathematics were a development of thinking around the 15-16th centuries – and grounded on theology, the God of the Bible.
Nature and Nature's laws lay hid
God said: "Let Newton be!"
and all was light.
Alexander Pope's famous couplet gives the impression that Newton's genius lay in his discovery of previously hidden laws of nature. This disguises what was both a novel feature of the science of the seventeenth century and its enduring legacy—the idea that there existed "laws of nature" to be discovered in the first place.
What are laws of nature? For the Middle Ages, natural laws had been universal moral rules established by God. The injunction against murder, recognized by all cultures, was a typical example of a natural law. The concept of a physical law of nature was completely absent. That came only as Christian thinkers extended God's legislative power to the natural world. As philosopher and scientist René Descartes (1596-1650) expressed it, "God alone is the author of all the motions in the world."
For its time, this was a radical claim. Following Aristotle, medieval scientists had imputed immanent tendencies to physical entities, saying for example that objects went into motion because they were seeking their own natural resting place. Nature had thus enjoyed a considerable degree of autonomy.
In the new science, however, natural objects had no inherent properties, and it was God who directly controlled their interactions. In much the same way that the Deity had instituted moral rules, he was now seen to have enacted laws that governed the natural world.
"Nature," observed Robert Boyle, "is nothing else but God acting according to certain laws he himself fix'd."
The fact that God was the author of these laws meant that they shared something of his nature. Descartes, for example, argued that because of their source, natural laws must be eternal and unchanging. He went on to justify his law of the conservation of motion by appealing to God's immutability. Nature was constant because God was immutable.
This provided a crucial foundation for experimental science. In the words of Newton's predecessor in the Lucasian Chair of Mathematics at Cambridge, Isaac Barrow, experimentalists "do not suspect that Nature is inconstant, and the great Author of the universe unlike himself." Only because they assume that God's decrees are unchanging do they expect the consistent results of a number of experiments to hold true ever after.