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By age 20, Erdős had already made significant strides in number theory, providing an elegant proof of Chebyshev’s theorem. This theorem asserts that for any number greater than one, there's always at least one prime between that number and its double. His academic journey took him from the University of Budapest to postdoctoral work in Manchester, and eventually to the United States, where he joined the Institute for Advanced Study in Princeton. Despite initial skepticism from the institute, his productivity thrived, often working from early morning until dawn. Erdős believed in the divine "Book"—a metaphorical collection of the most perfect proofs of mathematical theorems—despite being an atheist. He famously advised, “You don’t have to believe in God, but you should believe in The Book,” emphasizing his reverence for mathematical beauty and elegance.