Never sleeping, still awake, 
Pleasing most when most I speak; 
The delight of old and young, 
Though I speak without a tongue. 
Nought but one thing can confound me, 
Many voices joining round me; 
Then I fret, and rave, and gabble, 
Like the labourers of Babel. 
Now I am a dog, or cow, 
I can bark, or I can low; 
I can bleat, or I can sing, 
Like the warblers of the spring. 
Let the lovesick bard complain, 
And I mourn the cruel pain; 
Let the happy swain rejoice, 
And I join my helping voice: 
Both are welcome, grief or joy, 
I with either sport and toy. 
Though a lady, I am stout, 
Drums and trumpets bring me out: 
Then I clash, and roar, and rattle, 
Join in all the din of battle. 
Jove, with all his loudest thunder, 
When I'm vext, can't keep me under; 
Yet so tender is my ear, 
That the lowest voice I fear; 
Much I dread the courtier's fate, 
When his merit's out of date, 
For I hate a silent breath, 
And a whisper is my death.
Jonathan Swift
http://www.poemhunter.com/poem/an-echo/