Newton's apple

After the story that English scientist Isaac Newton was inspired to formulate his theory of gravitation by watching the fall of an apple from a tree.

Newton's apple (plural Newton's apples)

1. Something that acts as a source of inspiration or triggers an important realization for someone.
   • 1913, Archibald Allan, Space and Personality, Edinburgh: Oliver & Boyd, page 204:

     The 'perfect fluid' which Lord Kelvin desiderated, is an instance that scientists are on the outlook for something that will serve as a Newton's apple to lead them to the larger truth which urges birth from their instincts of faith.

   • 2010, Yuri Tsivian, “The Gesture of Revolution or Misquoting as Device”, in Annie van den Oever, editor, Ostrannenie: On "Strangeness" and the Moving Image: The History, Reception, and Relevance of a Concept, Amsterdam: Amsterdam University Press, →ISBN, page 25:

     Shortly afterwards, in a book called Stupeni. Tekst khudozhnika [Steps. An Artist's Text] published in 1918 in Moscow, Kandinsky wrote about himself as the original discoverer of abstract painting and, as is the custom of discoverers, recounted what precisely became his Newton's apple.