“We stand now at the turning point between two eras. Behind us is a past to which we can never return ... The coming of the rocket brought to an end a million years of isolation ... the childhood of our race was over and history as we know it began.”

Original: (pt) Isso fez do português este tipo que nós somos. Nós não temos raça nenhuma. Não se pode falar na raça portuguesa. Se houvesse uma raça, nós éramos uma anti-raça. Feita com gente vinda de toda a parte ao longo de milhões de anos.
Source: "História Essencial de Portugal", episode 1

Presidency (1977–1981), The Crisis of Confidence (1979)
Context: We know the strength of America. We are strong. We can regain our unity. We can regain our confidence. We are the heirs of generations who survived threats much more powerful and awesome than those that challenge us now. Our fathers and mothers were strong men and women who shaped a new society during the Great Depression, who fought world wars, and who carved out a new charter of peace for the world.
We ourselves are the same Americans who just 10 years ago put a man on the Moon. We are the generation that dedicated our society to the pursuit of human rights and equality. And we are the generation that will win the war on the energy problem and in that process rebuild the unity and confidence of America.
We are at a turning point in our history. There are two paths to choose. One is a path I've warned about tonight, the path that leads to fragmentation and self- interest. Down that road lies a mistaken idea of freedom, the right to grasp for ourselves some advantage over others. That path would be one of constant conflict between narrow interests ending in chaos and immobility. It is a certain route to failure.
All the traditions of our past, all the lessons of our heritage, all the promises of our future point to another path, the path of common purpose and the restoration of American values. That path leads to true freedom for our Nation and ourselves. We can take the first steps down that path as we begin to solve our energy problem.
Energy will be the immediate test of our ability to unite this Nation, and it can also be the standard around which we rally. On the battlefield of energy we can win for our Nation a new confidence, and we can seize control again of our common destiny.

The Gendered Atom: Reflections on the Sexual Psychology of Science (1999)
Context: Here, at the birth of modern science, is a fundamental insight. Our knowledge of nature Out There begins with knowledge of ourselves In Here. Until we have freed our minds and emotions of the hidden presuppositions that stand between us and the world, we can never be certain we are in touch with reality.

Afterword: The Idols of the Bedchamber

This is from a fictional speech by Lincoln which occurs in The Clansman : An Historical Romance of the Ku Klux Klan (1905) by Thomas Dixon, Jr.. On some sites this has been declared to be something Lincoln said "soon after signing" the Emancipation Proclamation, but without any date or other indications of to whom it was stated, and there are no actual historical records of Lincoln ever saying this.
Misattributed

Speech at Zurich University (September 19, 1946) ( partial text http://www.churchill-society-london.org.uk/astonish.html) ( http://www.peshawar.ch/varia/winston.htm).
Post-war years (1945–1955)

Nothing! This sphere, with its clinging tenantry, will still be here then and will still be making its annual journeys round the sun, as now. But, O, what mighty and ineffable changes! The things of to-day will be so rude and childish and so far away that they will not even be considered.
Source: Ethics and Education (1912), The World to Be, p. 149

Speech at the Coliseum, Raleigh, North Carolina" (17 September 1960) http://www.presidency.ucsb.edu/ws/?pid=74076
1960

The Lesson, Stanza 8 (1899-1902).
Other works