There are many quotes attributed to Bach. Probably one of the most well known is: “There's nothing remarkable about it. All one has to do is hit the right keys at the right time and the instrument plays itself.”
Another is: “I was obliged to be industrious. Whoever is equally industrious will succeed equally well.”
And, although I wish I knew something of the context in which this one was used, it is certainly one of my favorites: “If I decide to be an idiot, then I'll be an idiot on my own accord.”