Every single politician, everyone who's ever been president; or vice president, alive today either legally or in a case or two, illegally, should not only learn this word for word but have it branded on his hind side permanently with a fresh from the fire branding iron!! With maybe a few precious exceptions.
Specifically previous "presidents" who've soiled the presidency with their lies, outright treason, and becoming rich off that office. 

Indeed, truth must be known; sadly, what passes for "truth" is often highly suspect. There is One absolute Truth, and One only.
Too often over the years truth has been whatever one decided it should be...usually those in "power" determined to hang on to that power come hell or high water, at any cost...even lives. Might we be seeing that now?

"The press should be not only a collective propagandist and a collective agitator, but also a collective organizer of the masses." Vlademir Lenin...millions starved and shot to death.

"A lie repeated often enough becomes truth.
Joseph Goebbels   Hitler's "right" hand man. over 6 million Jews and other nationalities murdered.

"If the American people knew how we chose what to print, there would be rioting in the streets."  Wm. Randolph Hearst