“Where there is independence there must be the normal law.”

A Preliminary Discourse on the Study of Natural Philosophy (1831)
Context: We must never forget that it is principles, not phenomena, — laws not insulated independent facts, — which are the objects of inquiry to the natural philosopher. As truth is single, and consistent with itself, a principle may be as completely and as plainly elucidated by the most familiar and simple fact, as by the most imposing and uncommon phenomenon. The colours which glitter on a soapbubble are the immediate consequence of a principle the most important, from the variety of phenomena it explains, and the most beautiful, from its simplicity and compendious neatness, in the whole science of optics. If the nature of periodical colours can be made intelligible by the contemplation of such a trivial object, from that moment it becomes a noble instrument in the eye of correct judgment; and to blow a large, regular, and durable soap-bubble may become the serious and praise-worthy endeavour of a sage, while children stand round and scoff, or children of a larger growth hold up their hands in astonishment at such waste of time and trouble. To the natural philosopher there is no natural object unimportant or trifling. From the least of nature's works he may learn the greatest lessons. The fall of an apple to the ground may raise his thoughts to the laws which govern the revolutions of the planets in their orbits; or the situation of a pebble may afford him evidence of the state of the globe he inhabits, myriads of ages ago, before his species became its denizens.
And this, is, in fact, one of the great sources of delight which the study of natural science imparts to its votaries. A mind which has once imbibed a taste for scientific inquiry, and has learnt the habit of applying its principles readily to the cases which occur, has within itself an inexhaustible source of pure and exciting contemplations. One would think that Shakspeare had such a mind in view when he describes a contemplative man as finding

Letter http://press-pubs.uchicago.edu/founders/documents/a1_8_18s16.html to Judge Spencer Roane (6 September 1819)
1810s
Context: It should be remembered, as an axiom of eternal truth in politics, that whatever power in any government is independent, is absolute also; in theory only, at first, while the spirit of the people is up, but in practice, as fast as that relaxes. Independence can be trusted nowhere but with the people in mass. They are inherently independent of all but moral law.

Source: Faith Beyond Resentment: Fragments Catholic and Gay (2001), "Jesus' fraternal relocation of God", p. 81.

"Runaround" in Astounding Science Fiction (March 1942); later published in I, Robot (1950)
The Three Laws of Robotics (1942)

Robinson v. Bland (1760), 2 Burr. Part IV. 1084.

Quoted in "Stephen Hawking prepares for weightless flight", New Scientist (26 April 2007) http://www.newscientist.com/article/dn11722-stephen-hawking-prepares-for-weightless-flight.html

Source: Science and Statistics (1976), p. 795

Source: Enigmas Of Chance (1985), Chapter 3, The Search For The Meaning Of Independence, p. 55.