“As though there were a tie
And obligation to posterity.
We get them, bear them, breed, and nurse:
What has posterity done for us.
That we, lest they their rights should lose,
Should trust our necks to gripe of noose?”

Letter to William Strahan (1745); reported in Bartlett's Familiar Quotations, 10th ed. (1919).
Epistles

Quoted in "Enter Japan" - "Time Magazine" article - July 8, 1940

Colin Serjent, "Blake's 08, http://www.catalystmedia.org.uk/issues/nerve9/peter_blake.php Nerve, Autumn 2006
On producing serigraph prints to celebrate Liverpool as the 2008 European Capital of Culture.
Art

2013, Second Inaugural Address (January 2013)
Context: We, the people, still believe that our obligations as Americans are not just to ourselves, but to all posterity.  We will respond to the threat of climate change, knowing that the failure to do so would betray our children and future generations. Some may still deny the overwhelming judgment of science, but none can avoid the devastating impact of raging fires and crippling drought and more powerful storms. The path towards sustainable energy sources will be long and sometimes difficult. But America cannot resist this transition, we must lead it. We cannot cede to other nations the technology that will power new jobs and new industries, we must claim its promise. That’s how we will maintain our economic vitality and our national treasure -- our forests and waterways, our crop lands and snow-capped peaks. That is how we will preserve our planet, commanded to our care by God. That’s what will lend meaning to the creed our fathers once declared.

You Would Have Understood Me

No. 587 (20 August 1714).
The Spectator (1711–1714)

Napoleon : In His Own Words (1916)

Knox on the Declaration of Independence. Reported in David McCullough, 1776 (2005), p. 83.

Introduction, Sec. 1
De architectura (The Ten Books On Architecture) (~ 15BC), Book VII