|A parody of the "age 30 rule" of physics, namely that if one doesn't make their mark by their 30th birthday, they never will. |
In general fame, what is referred to as the “Holmes hypothesis”, cited by genius studies scholar Dean Simonton, states that the 40th year mark is the making or breaking point of genius. 
In physics, at least was the inside joke in the 1920s, the make or break point is said to be the 30th year, so later said Albert Einstein and Paul Dirac. In particular, the age 30 rule in physics seems to, unwrittenly, stem from Einstein’s 1905 age 26 so-called “miracle year” (Ѻ), during which he published four pioneering articles on: space, time, mass, and energy, which altered modern physics thereafter.
American genius studies scholar Dean Simonton, however, points out that: Newton published his Principia at 45, Kant his Critique of Pure Reason at 57, Copernicus his Revolution of the Heavenly Spheres at 70, as examples to contradict the above.
Outside of physics proper, the rule is inexact. Darwin, e.g., didn't publish Origin of Species (1859) until age 50.
hmolscience, the standing benchmark is the 1809 age 60 publication of Elective Affinities by Goethe. After Goethe, stepping a century ahead in time, in the field of inquiry of people are viewed as molecules or chemicals, the following (shown bolded) are the new general intellectual benchmarks:
Adams and Rossini both published their famous treatises at age 72, and Wallace published his magnum opus at 74.
Of note, is Vilfredo Pareto (SN:3), being that it is often said that he didn’t start his so-called "second career" until the second half of his reaction existence; specifically he didn’t initiated the start of his intellectual legacy until age 48 (Course on Political Economics), and didn’t complete his four-volume (Treatise on General Sociology magnum opus until age 64.
The following are related quotes:
“If you haven’t cut your name on the door of fame by the time you’ve reached 40, you might as well put up your jackknife.”— Oliver Wendell Holmes Jr. (c.1840), publication (Ѻ)
“You are now past 30 and you are no longer a physicist.”— Paul Dirac (1931), comment to Heisenberg shortly after his 30th birthday (Dec 5) 
“A person who has not made his great contribution to science before the age of thirty will never do so.”— Albert Einstein (c.1940), publication 
1. Cavazox-Gaither A.E. (2002). Chemically Speaking: A Dictionary of Quotations (pg. 9-10). CRC Press.
2. Einstein, Albert. (1942). “Publication” (Ѻ)(Ѻ); In: S. Brodetsky, “Newton: Scientist and Man”, Nature, 150(3815):699, Dec 12.
3. (a) Dirac, Paul. (1963). “Interview with von Weizsacher”, Archives for the History of Quantum Physics (pg. 19), Jun 9.
(b) Farmelo, Graham. (2009). The Strangest Man: the Hidden Life of Paul Dirac, Mystic of the Atom (pg. 230). Basic Books.
4. Simonton, Dean K. (1994). Greatness: Who Makes History and Why (pgs. 181-82). Guilford Press.