“[N]o law, written or unwritten, can be understood without a full knowledge of the facts out of which it arises, and to which it is to be applied.”

The Law
The Note-Books of Samuel Butler (1912), Part VII - On the Making of Music, Pictures, and Books
Context: The written law is binding, but the unwritten law is much more so. You may break the written law at a pinch and on the sly if you can, but the unwritten law — which often comprises the written — must not be broken. Not being written, it is not always easy to know what it is, but this has got to be done.

Wason v. Walter (1868), L. R. 4 Q. B. 93.

Thomas Taylor (Tr.) Political fragments of Archytas, Charondas, Zaleucus, and other Ancient Pythagoreans, preserved by Stobæus; and also, Ethical Fragments of Pierocles http://books.google.com/books?id=Kx4PAQAAMAAJ (1822)

Source: The Principles of Science: A Treatise on Logic and Scientific Method (1874) Vol. 1, p. 14

Ben Yamen's Song of Geometry (1853)
Context: The Key! it is of wonderful construction, with its infinity of combination, and its unlimited capacity to fit every lock. … it is the great master-key which unlocks every door of knowledge and without which no discovery which deserves the name — which is law, and not isolated fact — has been or ever can be made. Fascinated by its symmetry the geometer may at times have been too exclusively engrossed with his science, forgetful of its applications; he may have exalted it into his idol and worshipped it; he may have degraded it into his toy... when he should have been hard at work with it, using it for the benefit of mankind and the glory of his Creator.

"On the Harmony of Theory and Practice in Mechanics" (Jan. 3, 1856)
Context: Another evil, and one of the worst which arises from the separation of theoretical and practical knowledge, is the fact that a large number of persons, possessed of an inventive turn of mind and of considerable skill in the manual operations of practical mechanics, are destitute of that knowledge of scientific principles which is requisite to prevent their being misled by their own ingenuity. Such men too often spend their money, waste their lives, and it may be lose their reason in the vain pursuits of visionary inventions, of which a moderate amount of theoretical knowledge would be sufficient to demonstrate the fallacy; and for want of such knowledge, many a man who might have been a useful and happy member of society, becomes a being than whom it would be hard to find anything more miserable.
The number of those unhappy persons — to judge from the patent-lists, and from some of the mechanical journals — must be much greater than is generally believed.<!--p. 176

Silence is a Commons (1982)
Context: "Commons" is an Old English word. According to my Japanese friends, it is quite close to the meaning that iriai still has in Japanese. "Commons," like iriai, is a word which, in preindustrial times, was used to designate certain aspects of the environment. People called commons those parts of the environment for which customary law exacted specific forms of community respect. People called commons that part of the environment which lay beyond their own thresholds and outside of their own possessions, to which, however, they had recognized claims of usage, not to produce commodities but to provide for the subsistence of their households. The customary law which humanized the environment by establishing the commons was usually unwritten. It was unwritten law not only because people did not care to write it down, but because what it protected was a reality much too complex to fit into paragraphs. The law of the commons regulates the right of way, the right to fish and to hunt, to graze, and to collect wood or medicinal plants in the forest.
An oak tree might be in the commons. Its shade, in summer, is reserved for the shepherd and his flock; its acorns are reserved for the pigs of the neighbouring peasants; its dry branches serve as fuel for the widows of the village; some of its fresh twigs in springtime are cut as ornaments for the church — and at sunset it might be the place for the village assembly. When people spoke about commons, iriai, they designated an aspect of the environment that was limited, that was necessary for the community's survival, that was necessary for different groups in different ways, but which, in a strictly economic sense, was not perceived as scarce.

Introductory
The Grammar of Science (1900)

Inaugural Address of the Great Exhibition of the Works of Industry of All Nations, London (1851).
Context: Nobody who has paid any attention to the peculiar features of our present era will doubt for a moment that we are living at a period of most wonderful transition which tends rapidly to the accomplishment that great end to which, indeed, all history points—the realization of the unity of mankind.... The distances which separated the different nations and parts of the globe are rapidly vanishing before the achievements of modern invention, and we can traverse them with incredible ease; the languages of all nations are known, and their acquirement placed within the reach of everybody; thought is communicated with the rapidity and even by the power of lightning... The knowledge acquired becomes at once the property of all of the community at large... no sooner is a discovery or invention made, than it is already improved upon and surpassed by competing efforts: the products of all quarters of the globe are placed at our disposal, and we have only to choose which is the best and the cheapest for our purposes, and the powers of production are entrusted to the stimulus of competition and capital.... Science discovers these laws of power, motion and transformation; industry applies them to raw matter which the earth yields us in abundance, but which becomes valuable only by knowledge.