still waters run deep

• still water runs deep

Of Latin origin, but possibly popularized by William Shakespeare, c. 1590, in "Henry VI," part 2, act 3, scene 1:

Smooth runs the water where the brook is deep;

And in his simple show he harbours treason.

still waters run deep

1. A person with a calm appearance has, or may have, considerable inner emotion, character, or intellect.
   • 1822, Catharine Maria Sedgwick, A New-England Tale:

     I always knew she was an artful jade; 'still waters run deep;' but she shall be exposed, the mask shall be stripped from the hypocrite.

   • 1885, Thomas Hardy, A Mere Interlude:

     But still waters run deep; and no crisis had come in the years of her early maidenhood to demonstrate what lay hidden within her, like metal in a mine.

   • 1903, Samuel Butler, chapter 58, in The Way of All Flesh:

     Baxter had never known of any goings on in that quarter, but, bless you, still waters run deep, and these girls were all alike, one as bad as the other.

   • 2003 June 8, Alice Elliott Dark, “Book Review: Rainy Day Woman”, in New York Times, retrieved 9 July 2008:

     Isabel Pierce, the central character of Sweetwater, Roxana Robinson's fluid third novel, gives the appearance of being a thoughtful, reserved, quiet woman who won't rock any boats in her life. Yet she harbors passions; it might be said of her that still waters run deep.

• empty vessels make the most noise
• the calm before the storm

• Gregory Y. Titelman, Random House Dictionary of Popular Proverbs and Sayings, 1996, →ISBN, page 308.

• still water runs deep