Post-Newtonian dynamics caused a drastic change in what counts as a fundamental law of nature. Until then, basic laws had been bridges to metaphysics of substance or
body. In the late 1700s, the basic laws became just common premises for the local equations of motion that govern mechanical systems. This transformation had philosophical import: after 1800, the laws lose all connection to causality; they make the ontology of mechanics inscrutable; and it became a mystery what counts as evidence for the laws.