One of the distinguishing features of the OED is the illustrative quotations which accompany the etymological and definitional matter. These are the fruits of
...a systematic reading program directed by the editors, the consultation of supporting reference works, and the unsolicited submissions of interested readers and language hounds... [Willinsky 1994:11]Another effect of this reading program has been to skew citations according to the interests of the readers:
Thomas Austin, Esq., to take an extreme instance of citational profligacy, gathered some 165,000 citation slips (having culled cites from, among other works, fifty volumes of the Royal Society's Philosophical Transactions It's important not to take the quotations and dates to be the ultimate authority for the first occurrence or coinage of a word, and Willinsky's book is an extended examination of the limitations and difficulties of the OED. Some sources are disproportionately represented in quotations: Shakespeare's 32,868 citations, 1,904 new coinages attributed, and appearance in 14% of the dictionary's 240,000 main entries (in the First Edition --see Willinsky 1994:58) suggest that his works are the heart and soul of the language --perhaps arguable, but the numbers also reflect the existence of concordances which the editors of the OED used extensively. Willinsky again:
In order to appreciate the significance of Shakespeare's Victorian coronation as a king among English poets, one must realize the degree to which his later greatness was a process of 'reinventing' the playwright... The OED's investment in Shakespeare needs to be understood as part of a cultural production of interest and appreciation that resulted in, among other things, the concordances to the poet's plays. Shakespeare, in the two-and-a-half centuries since his death, had gradually been invested with the necessary authority for securing the language in the fashion desired by the Philological Society. [Willinsky 1994:64-65]Willinsky notes that some eras were dominated by particular forms of text; thus the sermon ("an early form of spoken essay and editorial... the center and substance of a free market in popular religious publishing" ) appears often, especially in the 17th century sources.
The first edition of the OED, in its particular patterns of favored and neglected sources, represents Victorian interests in the integration of theology and science, nation and empire... It's also worthwhile to pay attention to sources slighted by the editors of the First Edition, and the efforts made by subsequent editors to redress the grievances. Willinsky again:
The OED turned to literary heroes, the respectable press, and the reference trade as its primary sources of authority, but it also finds part of its power in the exclusion of texts and authors... slighting of the Romantics... considerable oversight shown towardIt's also vital to recognize that writers often use words more loosely than in the authoritative or 'dictionary' sense, and that "the nuances they bring to the accretion of meaning"  are what the dated examples attempt to exemplify. (Puns are an extremity of this: the point of a pun is that a word has multiple senses, and it doesn't just mean what it appears to mean ("I just brought carry-on luggage" "Didn't it smell bad?" [carry-on/carrion]).
- the highly influential Chancery court of the 15th century, which made a substantial contribution to the standardization of English;
- the working-class press movement that blossomed during the first half of the 19th century; and
- the entire body of women writers... 
And keep in mind that the OED isn't one thing, but a succession or even a process. The Second Edition is not the First completely re-edited, nor is it just the First plus the Supplements and the recent additions, and the editorial policies (which determined which words appeared and how they were supported with quotations) continue to evolve. Again, Willinsky is a fascinating guide to the (continuing) process of evolution.
The cyber-era appears to offer a search for meaning that need only stop short somewhere of a Borgean library of endless citation, in what amounts to the ultimate hypertext, linking each word to all of its uses in texts that span the English language and related root languages...