Newton's apple

plural Newton's apples

1. Something that acts as a source of inspiration or triggers an important realization for someone.

   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.

   1913, Archibald Allan, Space and Personality, Edinburgh: Oliver & Boyd, page 204

   1 more example

   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.

   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