Etymology
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butterfly (n.)

common name of any lepidopterous insect active in daylight, Old English buttorfleoge, evidently butter (n.) + fly (n.), but the name is of obscure signification. Perhaps based on the old notion that the insects (or, according to Grimm, witches disguised as butterflies) consume butter or milk that is left uncovered. Or, less creatively, simply because the pale yellow color of many species' wings suggests the color of butter. Another theory connects it to the color of the insect's excrement, based on Dutch cognate boterschijte. Also see papillon.

Applied to persons from c. 1600, originally in reference to vain and gaudy attire; by 1806 in reference to transformation from early lowly state; in reference to flitting tendencies by 1873. The swimming stroke so called from 1935. As a type of mechanical nut, 1869. Butterflies "light stomach spasms caused by anxiety" is from 1908. "Who breaks a butterfly upon a wheel?" is from Pope.

The butterfly effect is a deceptively simple insight extracted from a complex modern field. As a low-profile assistant professor in MIT's department of meteorology in 1961, [Edward] Lorenz created an early computer program to simulate weather. One day he changed one of a dozen numbers representing atmospheric conditions, from .506127 to .506. That tiny alteration utterly transformed his long-term forecast, a point Lorenz amplified in his 1972 paper, "Predictability: Does the Flap of a Butterfly's Wings in Brazil Set Off a Tornado in Texas?" [Peter Dizikes, "The Meaning of the Butterfly," The Boston Globe, June 8, 2008]
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I (pron.)

12c., a shortening of Old English ic, the first person singular nominative pronoun, from Proto-Germanic *ek (source also of Old Frisian ik, Old Norse ek, Norwegian eg, Danish jeg, Old High German ih, German ich, Gothic ik), from PIE *eg- "I," nominative form of the first person singular pronoun (source also of Sanskrit aham, Hittite uk, Latin ego (source of French Je), Greek ego, Russian ja, Lithuanian ).

Reduced to i by mid-12c. in northern England, later everywhere; the form ich or ik, especially before vowels, lingered in northern England until c. 1400 and survived in southern dialects until 18c. It began to be capitalized mid-13c. to mark it as a distinct word and avoid misreading in handwritten manuscripts.

The reason for writing I is ... the orthographic habit in the middle ages of using a 'long i' (that is, j or I) whenever the letter was isolated or formed the last letter of a group; the numeral 'one' was written j or I (and three iij, etc.), just as much as the pronoun. [Otto Jespersen, "Growth and Structure of the English Language," p.233]

The dot on the "small" letter -i- began to appear in 11c. Latin manuscripts to distinguish the letter from the stroke of another letter (such as -m- or -n-). Originally a diacritic, it was reduced to a dot with the introduction of Roman type fonts. The letter -y- also was written with a top dot in Old English and early Middle English, during the centuries when -i- tended to be written with a closed loop at the top and thus was almost indistinguishable from the lower-case thorn (þ). In names of U.S. highways (by 1966) it is short for Interstate (adj.).

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law (n.)
Origin and meaning of law

Old English lagu (plural laga, combining form lah-) "ordinance, rule prescribed by authority, regulation; district governed by the same laws;" also sometimes "right, legal privilege," from Old Norse *lagu "law," collective plural of lag "layer, measure, stroke," literally "something laid down, that which is fixed or set."

This is reconstructed to be from Proto-Germanic *lagam "put, lay" (from PIE root *legh- "to lie down, lay"). The modern word is thus a twin of lay (n.2) as "that which is set or established."

Rare in Old English, it ousted the more usual ae and also gesetnes, which also were etymologically "something placed or set." 

In physics, "a proposition which expresses the regular order of things," from 1660s. Law and order have been coupled since 1796. To lay down the law (1752) is pleonastic (the "law" in the figure is biblical law, laid down from the pulpit). Poor laws provided for the support of paupers at public expense; sumptuary laws restrained excesses in apparel, food, or luxuries.

It is more common for Indo-European languages to use different words for "a specific law" and for "law" in the general sense of "institution or body of laws," for example Latin lex "a law," ius "a right," especially "legal right, law."

Indo-European words for "a law" are most commonly from verbs for "to put, place, set, lay," such as Greek thesmos (from tithemi "to put, place"), Old English dom (from PIE *dhe- "to put, place, set"), Lithuanian įstatymas (from statyti "cause to stand, set up, establish"), Polish ustawa (from stać "stand"). Also compare Old English gesetnes (above), statute, from Latin statuere; German Gesetz "law," from Old High German gisatzida "a fixing, determination, assessment," with sezzen (modern German setzen) "to make sit, set, put."

Words for "law" in the general sense mostly mean etymologically "what is right" and often are connected with adjectives for "right" (themselves often figurative uses of words for "straight," "upright," "true," "fitting," or "usage, custom." Such are Greek nomos (as in numismatic); French droit, Spanish derecho, from Latin directus; Polish prawo, Russian pravo (from Old Church Slavonic pravŭ "straight," in the daughter languages "right"); also Old Norse rettr, Old English riht, Dutch recht, German Recht (see right (adj.1)).

[L]earn to obey good laws before you seek to alter bad ones [Ruskin, "Fors Clavigera"]
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