The Unofficial Law of Consonants:
The quantity of consonants in the English language is constant. If omitted in one place, they turn up in another. When a Bostonian "pahks" his "cah," the lost r's migrate southwest, causing a Texan to "warsh" his car and invest in "erl wells." ~Author Unknown
Unintuitive Terms:
English is a funny language; that explains why we park our car on the driveway and drive our car on the parkway. ~Author Unknown
The Confusion of Slang:
'There is correct English: that is not slang.'
'I beg your pardon: correct English is the slang of prigs who write history and essays. And the strongest slang of all is the slang of poets.'
~George Eliot, Middlemarch: A Study of Provincial Life, Volume I, Book I—Miss Brooke, 1871
Translations:
[The translator] has done his cleverest and best with this that follows, but you might as well seek to translate a violet into verse as seek to render in language other than its own the delicate sentiment, the exquisite rhythm, of the... original. ~William Cleaver Wilkinson, Classic German Course in English, 1887
Too Many Loan Words:
The problem with defending the purity of the English language is that English is about as pure as a cribhouse whore. We don't just borrow words; on occasion, English has pursued other languages down alleyways to beat them unconscious and rifle their pockets for new vocabulary. ~James D. Nicoll (b.1961), "The King's English," rec.arts.sf-lovers, 1990 May 15th
And of course, the constantly changing nature of all languages. But that's what gives them beauty, too.