… is from page 158 of the 1996 Liberty Fund collection of Frank Meyer’s essays, In Defense of Freedom (William C. Dennis, ed.); specifically, it’s from Meyer’s September 25, 1962, National Review article “Why Freedom”:
For men imbued with the certainty of their vision of reality it will always be difficult to restrain the temptation to enforce that vision upon others and thus to deprive them of the right freely to choose the good.