Vesti la giubba

Vesti la giubba (Put on the costume) is a famous tenor aria performed as part of the opera Pagliacci, written and composed by Ruggero Leoncavallo, and first performed in 1892. Vesti la giubba is the conclusion of the first act, when Canio discovers his wife's infidelity, but must nevertheless prepare for his performance as Pagliaccio the clown because 'the show must go on'.
The aria is often regarded as one of the most moving in the operatic repertoire of the time. The pain of Canio is portrayed in the aria and exemplifies the entire notion of the 'tragic clown': smiling on the outside but crying on the inside. This is still displayed today as the clown motif often features the painted on tear running down the cheek of the performer.
Since the opera's first performance in 1892, this aria in particular has ingrained itself well into popular culture, and has often been featured in many renditions, mentions, and spoofs over the years. The 1904 recording by Enrico Caruso was the first million-selling record in history

Translation in English
To act! While out of my mind,
I no longer know what I say,
or what I do!
And yet it's necessary... make an effort!
Bah! Are you not a man?
You are Pagliaccio!
Put on your costume,
powder your face.
The people pay to be here, and they want to laugh.
And if Harlequin shall steal your Columbine,
laugh, Pagliaccio, so the crowd will cheer!
Turn your distress and tears into jest,
your pain and sobbing into a funny face - Ah!
Laugh, Pagliaccio,
at your broken love!
Laugh at the grief that poisons your heart!

http://www.youtube.com/watch?v=Ky271W94VHA