The song by the American rock duo, Simon & Garfunkel, which contains the phrase "You're shaking my confidence daily" is "Cecilia". "Cecilia" was released in April 1970 and was the third single from the group's fifth studio album, "Bridge over Troubled Water" (1970). Written by Paul Simon, he said that the song's origins lie in a late-night party, in which he, Garfunkel, and a few friends began banging on a piano bench. They then recorded the sound with a tape recorder, employing reverb. They matched the rhythm created by the machine. Simon later wrote the song's guitar line and lyrics on the subject of an untrustworthy lover.

When released as a single, "Cecilia" reached No. 4 on the US charts. The single did not chart in the UK, despite being released as the follow-up to the duo's No. 1 hit “Bridge Over Troubled Water”.

Simon also suggested that the “Cecilia” of the title refers to St. Cecilia, the patron saint of musicians in the Catholic tradition. This means the song might refer to the frustration of fleeting inspiration in songwriting, the vagaries of musical fame, or the wide absurdity of some pointless singular issue hyped by teenage pop cultures in their music. This song however is generally and best interpreted as a lament over a capricious lover who causes both anguish and jubilation to the singer.

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