Abstemius's Fables (Sir Roger L'Estrange)
259. (Abstemius 5) A Country-man and a River.
A Country-man that was to pass a River, founded it up and down to try where it was most fordable: and upon Trial he made this Observation on't: Where the Water ran Smooth, he found it Deepest; and on the contrary, Shallowest where it made most Noise.
There's More Danger in a Reserv'd and Silent, than in a Noisy, Babbling Enemy.
Fables of Aesop and Other Eminent Mythologists: Abstemius's Fables by Sir Roger L'Estrange. Available online at Google Books.