Say that you're writing a book, a magazine article, or some other work in a medium that (1) doesn't allow hyperlinking, and (2) discourages footnoting. And say that you want to quote a phrase you much like — for instance, "The past is a foreign country; they do things differently there."
Naturally, you should quote it, to make clear that you're not claiming authorship. But must you give credit to the author, for instance, "as L.P. Hartley wrote, '...'"? In an earlier time, I would think you should, unless the line was so cliché that its source would be familiar to most readers. (By the way, should it have mattered whether the author was long-dead?) After all, you ought to give credit where credit is due.
But these days, for many such quotes, the attribution is only a google search away — not much harder, generally speaking, than looking up the quote in an endnote, which would be considered a perfectly acceptable way to give credit in those media that allow endnotes. So assume that the google search does indeed yield the proper attribution. Does that relieve you of the obligation to mention the author in your work (again, assuming you include the quotes)? Or should you still mention the author's name somewhere, given that not everyone will be reading your piece with a computer around, or perhaps based on some deeper inherent obligation to give credit in your own work? Or might the ethical question be moot, because the text without the attribution — for instance,
"The past is a foreign country: they do things differently there." Among other things, they speak a foreign language....
-- looks clumsy enough that you ought to add "In L.P. Hartley's words" or some such just to make the text flow better?
UPDATE: Well, there's remarkable unanimity in the comments, and they all answer the question in the title with "no." Fortunately for me, I generally write in media where footnotes and endnotes are allowed, so I can avoid the "As x says" locution and yet give full credit directly in my own work. In any case, thanks for the feedback!