“The spirit of the Japanese nation is, by its nature, a thing that must be propagated over the seven seas and extended over the five continents. Anything that may hinder its progress must be abolished, even by force.”

Preface
The Great Rehearsal (1948)
Context: The parallel between 1787 and 1948 is naturally not exact. Even if it were, 1787 would have no authority over 1948. Each age must make or keep its own government and determine its own future. Nor do those citizens of the world who In 1948 desire to see a federal world government created assume that the process would have to follow the example of the United States of 1787 in the details of the new government. The Federal Convention did not follow any single example. Neither should a General Conference of the United Nations be expected to.

Achtung-Panzer! : The Development of Armoured Forces, Their Tactics and Operational Potential (1937)

Source: The Geological Evidences of the Antiquity of Man (1863), Ch.21, p. 411-412
Context: The competition of races and species, observes Mr. Darwin, is always most severe between those which are most closely allied and which fill nearly the same place in the economy of nature. Hence, when the conditions of existence are modified, the original stock runs great risk of being superseded by some one of its modified offshoots. The new race or species may not be absolutely superior in the sum of its powers and endowment to the parent stock, and may even be more simple in structure and of a lower grade of intelligence, as well as of organisation, provided, on the whole, it happens to have some slight advantage over its rivals. Progression, therefore, is not a necessary accompaniment of variation and natural selection, though, when a higher organisation happens to be coincident with superior fitness to new conditions, the new species will have greater power and a greater chance of permanently maintaining and extending its ground.

Source: The Freedom of a Christian (1520), pp. 71-72

Source: The National System of Political Economy (1841), p. 365

The original anecdote from whence Kennedy derived this comparison is in An Only Child, Frank O'Connor, London: MacMillan & Co. Ltd., 1961; p. 180.
1963, President John F. Kennedy's last formal speech and public words
Context: This Nation has tossed its cap over the wall of space, and we have no choice but to follow it. Whatever the difficulties, they will be overcome. Whatever the hazards, they must be guarded against. With the vital help of this Aerospace Medical Center, with the help of all those who labor in the space endeavor, with the help and support of all Americans, we will climb this wall with safety and with speed-and we shall then explore the wonders on the other side.

Source: Defeat Into Victory (1961), p. 447

The Economics of Ireland and the Policy of the British Government (1921)