“Amid the pressure of great events, a general principle gives no help.”

On War (1832), Book 3

1920s, Speech on the Anniversary of the Declaration of Independence (1926)

1920s, The Genius of America (1924)
Context: This is the main thought which your presence here brings to my mind. Let us maintain all the high ideals which have been characteristic of our different races at home. Let us keep our desire to help other lands as a great and broad principle, not to help in one place and do harm in another, but to render assistance everywhere. Let us remember also that the best method of promoting this action is by giving undivided allegiance to America, maintaining its institutions, supporting its Government, and, by leaving it internally harmonious, making it eternally powerful in promoting a reign of justice and mercy throughout the earth.

Comme nous ne pouvons pas donner de l'énergie une définition générale, le principe de la conservation de l'énergie signifie simplement qu'il y a quelque chose qui demeure constant.
Source: The Value of Science (1905), Ch. 10: Is Science artificial?

Epistulae Morales ad Lucilium (Moral Letters to Lucilius), Letter XXXVII: On Allegiance to Virtue

Day of Affirmation Address (1966)
Variant: Few will have the greatness to bend history, but each of us can work to change a small portion of the events, and then the total — all of these acts — will be written in the history of this generation.

Source: Why We Fail as Christians (1919), p. 63
Context: When principles will not work out in practice and the obstructions confronting men are too great, even the most faithful give way. And this, so far as we know, is what happened to every Tolstoyan.

Introduction.
On the Complexity of Causal Models (1977)

1970s, Synergetics: Explorations in the Geometry of Thinking (1975), Afterpiece
Context: We evolute toward ever lesser brain comprehension lags — ergo, toward ever diminishing error; ergo, ever diminishing misunderstandings; ergo, ever diminishing fear, and its brain-lagging painful errors of objectivity; wherefore we approach eternal instantaneity of absolute and total comprehension. The eternal instantaneity of no lag at all. However, we have now learned from our generalizations of the great complexity of the interactions of principles as we are disembarrassed of our local, exclusively physical chemistry of information-sensing devices — that what is approached is eternal and instant awareness of absolute reality of all that ever existed. All the great metaphysical integrity of all the individuals, which is potential and inherent in the complex interactions of generalized principles, will always and only coexist eternally.