What were the rock solid principles upon which Reagan believed the American “Shining City on a Hill” was built? [closed]

President Reagan in his farewell address spoke of America as a shining city on a hill:

[I]n my mind it was a tall, proud city built on rocks stronger than oceans, windswept, God-blessed, and teeming with people of all kinds living in harmony and peace; a city with free ports that hummed with commerce and creativity. And if there had to be city walls, the walls had doors and the doors were open to anyone with the will and the heart to get here.

He reminded us that:

[A]s long as we remember our first principles and believe in ourselves, the future will always be ours

What I have been pondering given the divisions among Americans is what those rock-solid principles were in 1989? Do we still believe they are rock solid today?

Is America today still built upon those same rocks, our have we chosen different principles?