1.
If it looks like a duck, quacks like a duck, it's a duck!
Robin Cook
2.
An optimist is someone who figures that if it walks like a duck and quacks like a duck, it's the bluebird of happiness.
Robert Breault
4.
Nothing is more despicable than a professional talker who uses his words as a quack uses his remedies
Francois Fenelon
6.
Take the humbug out of this world, and you haven't much left to do business with.
Josh Billings
7.
I have never been converted to or even had much interest in spiritualism, occultism, Swedenborgianism or any particular religion. And I never, except occasionally for a laugh, visit the quacks who call themselves psychics.
Dick Cavett
8.
Let us leave the cure of public evils to those quacks,
the statesmen.
Honore de Balzac
9.
When it walks like a saint, and quacks like a saint- it's a quacking saint." -Della
C.C. Hunter
10.
Because Mathematicians frequently make use of Time, they ought to have a distinct idea of the meaning of that Word, otherwise they are Quacks.
Isaac Barrow
11.
(about Dr. Po) Just another quack spouting psychobabble.
Eoin Colfer