The Secret
Its author has stated she first encountered the core teaching in a 1910 American self-help pamphlet, which the book closely restates. The 'ancient secret known to Newton and Beethoven' framing has no basis; its actual, traceable textual parent is a specific, dated early-twentieth-century book.
Rhonda Byrne, The Secret (2006); Wallace Wattles, The Science of Getting Rich (1910)
A 2006 book and film that became one of the best-selling self-help works of the twenty-first century, marketed as a suppressed ancient law of attraction.