careering on the utmost verge

I write diligently, but not so rapidly as I had hoped. I find the book requires more care and thought than the "Scarlet Letter"; -- also, I have to wait oftener for a mood. The Scarlet Letter being all in one tone, I had only to get my pitch, and could then go on interminably. Many passages of this book ought to be finished with the minuteness of a Dutch picture, in order to give them their proper effect. Sometimes, when tired of it, it strikes me that the whole is an absurdity, from beginning to end; but the fact is, in writing a romance, a man is always -- or always ought to be -- careering on the utmost verge of a precipitous absurdity, and the skill lies in coming as close as possible, without actually tumbling over.

-- Nathaniel Hawthorne, on the writing of The House of the Seven Gables, Letter to James T. Fields (3 November 1850)