“We have to do it for our children and for our grandchildren and so that this profound experiment in ordered liberty that was bequeathed to us by Madison and Washington and Hamilton and Adams and by Lincoln doesn't collapse. That republican government, which is ultimately what's at stake here, because a licentious people is not going to sustain republican government. We've got to make sure that republican government, government not only of the people as all government is but by and for the people doesn't perish from the Earth. If we lose it here, it's not as if it's going to be restarted somewhere else. People look to the United States to see if whether self-government can actually work and it's not going to work unless we as individual people and as members of small communities, institutions of civil society, are able to govern ourselves or are able to control our own passions and desires.”

1980s, Second term of office (1985–1989), Farewell Address (1989)

26 June 1787 per page 105 of "The Debates, Resolutions, and Other Proceedings, in Convention, on the Adoption of the Federal Constitution: Supplementary to the state Conventions" by Johnathan Elliot, published 1830 https://books.google.ca/books?id=-gtAAAAAYAAJ&pg=RA1-PA105
Debates of the Federal Convention (1787)

Chap. 2. Rights and the Neutral States
Democracy's Discontent (1996)

1870s, Message to the Senate and House of Representatives (1870)
Context: The framers of our Constitution firmly believed that a republican government could not endure without intelligence and education generally diffused among the people. The Father of his Country, in his Farewell Address, uses this language: Promote, then, as an object of primary importance, institutions for the general diffusion of knowledge. In proportion as the structure of a government gives force to public opinion, it is essential that public opinion should be enlightened.

"Fooling the People as a Fine Art", La Follette's Magazine (April 1918)

2000s, Speech at the Republican National Convention (31 August 2004)

1871, Speech on the the Ku Klux Klan Bill of 1871 (1 April 1871)

Reception in Winder, Georgia, September 11, 2003. http://renewamerica.us/archives/speeches/03_09_11reception.htm.
2009

1790s, Farewell Address (1796)
Source: George Washington's Farewell Address
Context: Hence, likewise, they will avoid the necessity of those overgrown military establishments, which, under any form of government, are inauspicious to liberty, and which are to be regarded as particularly hostile to Republican Liberty.
Context: While, then, every part of our country thus feels an immediate and particular interest in Union, all the parts combined cannot fail to find in the united mass of means and efforts greater strength, greater resource, proportionably greater security from external danger, a less frequent interruption of their peace by foreign nations; and, what is of inestimable value, they must derive from Union an exemption from those broils and wars between themselves, which so frequently afflict neighbouring countries not tied together by the same governments, which their own rivalships alone would be sufficient to produce, but which opposite foreign alliances, attachments, and intrigues would stimulate and embitter. Hence, likewise, they will avoid the necessity of those overgrown military establishments, which, under any form of government, are inauspicious to liberty, and which are to be regarded as particularly hostile to Republican Liberty. In this sense it is, that your Union ought to be considered as a main prop of your liberty, and that the love of the one ought to endear to you the preservation of the other.