Why were Isaac Newton and John Locke considered major influences on the Enlightenment?

Isaac Newton and John Locke are considered the "fathers of the Enlightenment" because their work provided the intellectual foundation for the 18th-century belief in the authority and autonomy of reason.12

Isaac Newton

Newton’s Philosophiae Naturalis Principia Mathematica (1687) represented the culmination of the scientific revolution. By applying mathematics to nature in exhaustive detail, he created a comprehensive, mechanistic system that appeared to finally unlock nature's secrets. This achievement convinced thinkers from Locke to Kant that human reason was capable of conquering the natural world, offering a sense of certainty in an era of doubt.123

John Locke

Locke was a foundational figure in modern empiricism and political liberalism. His philosophy, which emphasized the use of reason to discover natural laws and duties, aligned with the scientific spirit of his contemporaries, including Newton. His advocacy for the social contract and religious toleration became central tenets of Enlightenment thought and significantly influenced the development of modern democratic governance.45