Source: Wings of Fire p. 90.
“Man needs difficulties; they are necessary for health.”
C.G. Jung (1875–1961) Swiss psychiatrist and psychotherapist who founded analytical psychology
"The Transcendent Function" http://books.google.com/books?id=L3bsAAAAMAAJ&q=%22Man+needs+difficulties+they+are+necessary+for+health%22&pg=PA73#v=onepage ("Die Transzendente Funktion") (1916) <br class="br">Volume 8: Structure & Dynamics of the Psyche, The Collected Works of C. G. Jung (1969)
Confucius (-551–-479 BC) Chinese teacher, editor, politician, and philosopher
Variant: The man of virtue makes the difficulty to be overcome his first business, and success only a subsequent consideration: this may be called perfect virtue.
Source: The Analects, Other chapters
Prince Philip, Duke of Edinburgh (1921) member of the British Royal Family, consort to Queen Elizabeth II
World Wildlife Fund: British National Appeal Banquet, London (1962)
The Environmental Revolution: Speeches on Conservation, 1962–77 (1978)
Context: For conservation to be successful it is necessary to take into consideration that it is a characteristic of man that he can only be relied upon to do anything consistently which is in his own interest. He may have occasional fits of conscience and moral rectitude but otherwise his actions are governed by self-interest. It follows then that whatever the moral reasons for conservation it will only be achieved by the inducement of profit or pleasure.
Isaac Asimov book The Tragedy of the Moon
"The Tragedy of the Moon," The Magazine of Fantasy and Science Fiction (July 1972)
General sources
Josiah Willard Gibbs (1839–1903) physicist
Quoted by C. S. Hastings in "Biographical Memoir of Josiah Willard Gibbs 1839-1903," National Academy of Sciences Biographical Memoirs, vol. VI (Washington, D.C.: National Academy of Sciences, 1909), p. 390. Complete memoir http://books.nap.edu/html/biomems/jgibbs.pdf <br class="br">Attributed
Kirby Page (1890–1957) American clergyman
Individualism and Socialism (1933)
“When a man’s success becomes commonplace to him, it is his success no longer.”
Henry S. Haskins (1875–1957)
Source: Meditations in Wall Street (1940), p. 104
Bran Ferren (1953) American technologist
To create for the ages, let's combine art and engineering, Bran, Ferren, January 23, 2018, www.ted.com, March 2014 https://www.ted.com/talks/bran_ferren_to_create_for_the_ages_let_s_combine_art_and_engineering,
