“If the earth were not round, heavy bodies would not tend from every side in a straight line towards the center of the earth, but to different points from different sides.”

Source: Essays: First Series

Book 1, Proposition 9.
On the Equilibrium of Planes

Book 1, Proposition 13.
On the Equilibrium of Planes

[Robert Evans, 2002, http://www.imdb.com/title/tt0303353, The Kid Stays in the Picture, Documentary, Highway Films]
The unreliable narrator

As quoted by Bryant, ibid., p. 36
Astronomia nova (1609)

1961, Inaugural Address
Context: So let us begin anew — remembering on both sides that civility is not a sign of weakness, and sincerity is always subject to proof. Let us never negotiate out of fear. But let us never fear to negotiate.
Let both sides explore what problems unite us instead of belaboring those problems which divide us. [... ] Let both sides seek to invoke the wonders of science instead of its terrors. Together let us explore the stars, conquer the deserts, eradicate disease, tap the ocean depths, and encourage the arts and commerce.
Let both sides unite to heed in all corners of the earth the command of Isaiah — to "undo the heavy burdens … and to let the oppressed go free."

Introduction to the "Corners on the Curving Sky" section of the book Soulscript (1970) compiled by Jordan. These lines have been widely published in verse format as work misattributed to Gwendolyn Brooks, usually as a poem titled "Corners on the Curving Sky." One website http://web.archive.org/20090809112040/www.geocities.com/juscurious/anon.html indicated that Brooks had publicly repudiated the attribution of these lines to her, but the misattribution seems to have long remained largely unrecognized.
Context: Our earth is round, and, among other things, that means that you and I can hold completely different points of view and both be right. The difference of our positions will show stars in your window I cannot even imagine. Your sky may burn with light, while mine, at the same moment, spreads beautiful to darkness. Still we must choose how we separately corner the circling universe of our experience. Once chosen, our cornering will determine the message of any star and darkness we encounter. These poems speak to philosophy; they reveal the corners where we organize what we know.

The above statements have been widely published in the above format as lines of verse attributed to Brooks, usually as a poem titled "Corners on the Curving Sky" — but one website http://web.archive.org/20090809112040/www.geocities.com/juscurious/anon.html indicated that she declared she did not write them. The words actually occur as an introduction to the "Corners on the Curving Sky" section of the book Soulscript (1970) compiled by June Jordan, in which other poems of Brooks were included, and thus is apparently the work of Jordan. It appears simply in paragraph form and reads thus:
Misattributed, "Corners on the Curving Sky"
Context: Our earth is round, and, among other things
That means that you and I can hold completely different
Points of view and both be right.
The difference of our positions will show
Stars in your window I cannot even imagine.
Your sky may burn with light,
While mine, at the same moment,
Spreads beautiful to darkness.