Discretion

Melanie Bush claimed that discretion was her middle name. (TV: Delta and the Bannermen)

"Discretion is the better part of valour" was a quote by William Shakespeare. (AUDIO: The Red Lady) This phrase was used by, at least, the First, (TV: The Chase) Second, (TV: The Abominable Snowmen) Fourth, (TV: The Ark in Space) and Sixth Doctors. (TV: The Twin Dilemma, The Mark of the Rani) Liv Chenka once misquoted the line as "discretion might be the better part of valour". (AUDIO: The Red Lady)

John, the landlord of 11 Cardinal Road, claimed that discretion was second nature to a man such as himself. (TV: Knock Knock)

Dorium Maldovar once described the Silence as "a religious order of great power and discretion". (TV: The Wedding of River Song)