“By denying scientific principles, one may maintain any paradox.”

Source: The Thing (1929), Ch. IV : The Drift From Domesticity
Context: In the matter of reforming things, as distinct from deforming them, there is one plain and simple principle; a principle which will probably be called a paradox. There exists in such a case a certain institution or law; let us say, for the sake of simplicity, a fence or gate erected across a road. The more modern type of reformer goes gaily up to it and says, "I don't see the use of this; let us clear it away." To which the more intelligent type of reformer will do well to answer: "If you don't see the use of it, I certainly won't let you clear it away. Go away and think. Then, when you can come back and tell me that you do see the use of it, I may allow you to destroy it."
This paradox rests on the most elementary common sense. The gate or fence did not grow there. It was not set up by somnambulists who built it in their sleep. It is highly improbable that it was put there by escaped lunatics who were for some reason loose in the street. Some person had some reason for thinking it would be a good thing for somebody. And until we know what the reason was, we really cannot judge whether the reason was reasonable. It is extremely probable that we have overlooked some whole aspect of the question, if something set up by human beings like ourselves seems to be entirely meaningless and mysterious. There are reformers who get over this difficulty by assuming that all their fathers were fools; but if that be so, we can only say that folly appears to be a hereditary disease. But the truth is that nobody has any business to destroy a social institution until he has really seen it as an historical institution. If he knows how it arose, and what purposes it was supposed to serve, he may really be able to say that they were bad purposes, or that they have since become bad purposes, or that they are purposes which are no longer served. But if he simply stares at the thing as a senseless monstrosity that has somehow sprung up in his path, it is he and not the traditionalist who is suffering from an illusion.

Part I, Essay 9: Of The Parties of Great Britain; final lines of this essay in the 1741 and 1742 editions of Essays, Moral and Political, they were not included in later editions.
Essays, Moral, Political, and Literary (1741-2; 1748)

Source: The Logic of Scientific Discovery (1934), Ch. 2 "On the Problem of a Theory of Scientific Method", Section XI: Methodological Rules as Conventions

Source: De architectura (The Ten Books On Architecture) (~ 15BC), Book I, Chapter I, Sec. 3

Ram Gopal, Indian Muslims: A Political History (1858-1947), pp. 264-65. quoted from Lal, K. S. (1992). The legacy of Muslim rule in India. New Delhi: Aditya Prakashan. Chapter 8

"On the Harmony of Theory and Practice in Mechanics" (Jan. 3, 1856)

Wording in Ideas and Opinions: It is therefore easy to see why the churches have always fought science and persecuted its devotees. On the other hand, I maintain that the cosmic religious feeling is the strongest and noblest motive for scientific research. Only those who realize the immense efforts and, above all, the devotion without which pioneer work in theoretical science cannot be achieved are able to grasp the strength of the emotion out of which alone such work, remote as it is from the immediate realities of life, can issue. What a deep conviction of the rationality of the universe and what a yearning to understand, were it but a feeble reflection of the mind revealed in this world, Kepler and Newton must have had to enable them to spend years of solitary labor in disentangling the principles of celestial mechanics! Those whose acquaintance with scientific research is derived chiefly from its practical results easily develop a completely false notion of the mentality of the men who, surrounded by a skeptical world, have shown the way to kindred spirits scattered wide through the world and through the centuries. Only one who has devoted his life to similar ends can have a vivid realization of what has inspired these men and given them the strength to remain true to their purpose in spite of countless failures. It is cosmic religious feeling that gives a man such strength. A contemporary has said, not unjustly, that in this materialistic age of ours the serious scientific workers are the only profoundly religious people.
1930s, Religion and Science (1930)
Variant: I assert that the cosmic religious experience is the strongest and noblest driving force behind scientific research.
Source: The World As I See It
Context: It is, therefore, quite natural that the churches have always fought against science and have persecuted its supporters. But, on the other hand, I assert that the cosmic religious experience is the strongest and noblest driving force behind scientific research. No one who does not appreciate the terrific exertions, and, above all, the devotion without which pioneer creations in scientific thought cannot come into being, can judge the strength of the feeling out of which alone such work, turned away as it is from immediate practical life, can grow. What a deep faith in the rationality of the structure of the world and what a longing to understand even a small glimpse of the reason revealed in the world there must have been in Kepler and Newton to enable them to unravel the mechanism of the heavens in long years of lonely work! Any one who only knows scientific research in its practical applications may easily come to a wrong interpretation of the state of mind of the men who, surrounded by skeptical contemporaries, have shown the way to kindred spirits scattered over all countries in all centuries. Only those who have dedicated their lives to similar ends can have a living conception of the inspiration which gave these men the power to remain loyal to their purpose in spite of countless failures. It is the cosmic religious sense which grants this power. A contemporary has rightly said that the only deeply religious people of our largely materialistic age are the earnest men of research.

The Psychology of Religion (1927), p. 48.

Letter to John Wayles Eppes (9 September 1814). Published in The Works of Thomas Jefferson in Twelve Volumes http://oll.libertyfund.org/ToC/0054.php, Federal Edition, Paul Leicester Ford, ed., New York: G. P. Putnam's Sons, 1904, Vol. 11 http://files.libertyfund.org/files/807/0054-11_Bk.pdf, pp. 425-426
1810s
Context: [... ] Congress itself can punish Alexandria, by repealing the law which made it a town, by discontinuing it as a port of entry or clearance, and perhaps by suppressing it’s banks. But I expect all will go off with impunity. If our government ever fails, it will be from this weakness. No government can be maintained without the principle of fear as well as of duty. Good men will obey the last, but bad ones the former only.