“Unwittingly then had I discovered an Invisible Empire of the Air, intangible, yet solid as granite, whose structure shall persist while man inhabits the planet.”

The Fair Singer.

St. 5.
The Age of Bronze (1823)
Context: While Franklin's quiet memory climbs to heaven,
Calming the lightning which he thence hath riven,
Or drawing from the no less kindled earth
Freedom and peace to that which boasts his birth;
While Washington's a watchword, such as ne'er
Shall sink while there's an echo left to air.

Source: The Hitchhiker's Guide to the Galaxy

Source: How to Save a Life

Source: The Kite Runner

Book 1, p. 1
Cosmotheoros (1695; publ. 1698)

Letter IV : Heloise to Abelard
Letters of Abelard and Heloise
Context: The heart of man is a labyrinth, whose windings are very difficult to be discovered. The praises you give me are the more dangerous, in regard that I love the person who gives them. The more I desire to please you, the readier am I to believe all the merit you attribute to me. Ah, think rather how to support my weaknesses by wholesome remonstrances! Be rather fearful than confident of my salvation: say our virtue is founded upon weakness, and that those only will be crowned who have fought with the greatest difficulties: but I seek not for that crown which is the reward of victory, I am content to avoid only the danger. It is easier to keep off than to win a battle. There are several degrees in glory, and I am not ambitious of the highest; those I leave to souls of great courage, who have been often victorious. I seek not to conquer, out of fear lest I should be overcome. Happy enough, if I can escape shipwreck, and at last gain the port. Heaven commands me to renounce that fatal passion which unites me to you; but oh! my heart will never be able to consent to it. Adieu.

Notes Toward a Supreme Fiction (1942), It Must Be Abstract

1963, American University speech
Variant: For in the final analysis, our most basic common link, is that we all inhabit this small planet, we all breathe the same air, we all cherish our children's futures, and we are all mortal.
Source: Profiles in Courage
Context: In short, both the United States and its allies, and the Soviet Union and its allies, have a mutually deep interest in a just and genuine peace and in halting the arms race. Agreements to this end are in the interests of the Soviet Union as well as ours — and even the most hostile nations can be relied upon to accept and keep those treaty obligations, and only those treaty obligations, which are in their own interest. So, let us not be blind to our differences — but let us also direct attention to our common interests and to the means by which those differences can be resolved. And if we cannot end now our differences, at least we can help make the world safe for diversity. For, in the final analysis, our most basic common link is that we all inhabit this small planet. We all breathe the same air. We all cherish our children's future. And we are all mortal.