“Those who preach the nonsense of eternal peace do not understand Aryan national life.”

Biographies of Words and the Home of the Aryas (1888)

This and many similar quotes with the same general meaning are misattributed to Aristotle as a result of Twitter attribution decay. The original source of the quote remains anonymous. The oldest reference resides in the works of George Bernard Shaw, Man and Superman (1903): "Maxims for Revolutionists", where he claims that “He who can, does. He who cannot, teaches.”. However, the related quote, "Those who can, do. Those who understand, teach" likely originates from Lee Shulman in his explanation of Aristotlean views on professional mastery: Source: Shulman, L. S. (1986). Those who understand: Knowledge growth in teaching. Educational Researcher, 15(2), 4 - 14. Stable URL: http://www.jstor.org/stable/1175860
Misattributed
Variant: Those who can, do, those who cannot, teach.

Letter to Louis Untermeyer (8 July 1915)
1910s

Variant: He who would live must fight. He who doesn't wish to fight in this world, where permanent struggle is the law of life, has not the right to exist.
Source: Mein Kampf

1900s, The Strenuous Life: Essays and Addresses (1900), The Strenuous Life

Source: Lord of Shadows

6.4311
Der Tod ist kein Ereignis des Lebens. Den Tod erlebt man nicht. Wenn man unter Ewigkeit nicht unendliche Zeitdauer, sondern Unzeitlichkeit versteht, dann lebt der ewig, der in der Gegenwart lebt. Unser Leben ist ebenso endlos, wie unser Gesichtsfeld grenzenlos ist.
1920s, Tractatus Logico-Philosophicus (1922)
Variant: Death is not an event of life. Death is not lived through.
If by eternity is understood not endless temporal duration but timelessness, then he lives eternally who lives in the present.
Our life is endless in the way that our visual field is without limit.

Source: Attributed, Dictionary of Burning Words of Brilliant Writers (1895), P. 265.