"Silent Cal" Coolidge wasn't quite as
silent as he's often made out to be.
It's true that he tended to use his words with efficiency and didn't allow himself to be quoted often, but this not only was his own personal way, it was part of the image of him that the country needed (and has been all to eager to perpetuate). After the scandals and excesses during Warren G. Harding's running of the administration, America needed a conservative, trustworthy, sober leader to bring back integrity, dignity, and respect to the office of the presidency—making good on the (somewhat ironic) "Return to Normalcy" promise used when Harding and he ran in 1920. Vice President Coolidge was able to do that.
As for the "silent" and suggestions that he rarely spoke much, he was known to be quite talkative when not speaking in public. And when he was in public, he did his share of speaking. In press conferences—he held three a week—he spoke well and easily on the subjects at hand. In fact, he gave more radio addresses than Franklin D. Roosevelt. He also gave more interviews to the press than any prior president. Though he personally disliked wasting time with idle chatter, it was not uncalculated in a political sense: he once told newly elected Herbert Hoover that "if you don't say anything, you won't be called on to repeat it."
Another thing that added to the image of the laconic Coolidge was his excellent dry wit. This, of course, made for entertaining quotes (so many that it's possible a few are apocryphal) which in turn make it appear that he tended to answer things with quips or one liners. His reputation, itself, helped fuel the image and he made no attempt to refute it.
(Sources: Richard Shenkman's Legends, Lies, and Cherished Myths of American History, 1988, www.britannica.com, a January 1996 article from The Yankee found at www.noho.com/calvinc.html, www.uniontrib.com/news/travel/20010312-0921-trv-travel-c.html)