Laudator Temporis Acti

Tacitus, Annals 4.69.3 (28 A.D.; tr. A.J. Woodman):

At no other time was the community more tense and panicked, behaving most cautiously of all toward those closest to them: encounters, dialogues, familiar and unfamiliar ears were avoided; even dumb and inanimate objects such as a roof and walls were treated with circumspection.

non alias magis anxia et pavens civitas, <cautissime> agens adversum proximos; congressus, conloquia, notae ignotaeque aures vitari; etiam muta atque inanima, tectum et parietes circumspectabantur.

<cautissime> agens Martin: egens M: <t>egens Lipsius: <se t>egens Vertranius: <sui t>egens Müller: reticens Weissenborn

A.J. Woodman ad loc:

The conceit is not simply that 'the walls have ears' but that they can speak and thus repeat what they have heard: for this complex of ideas see Fraenkel on Aesch. Ag. 37, Dyck on Cic. Cael. 60; Otto 266, Tosi 106 §230; Santoro L'Hoir 166 7.¹³³ muta atque inanima (again at H. 1.84.4) is a fairly common combination (Cic. Verr. 5.171, ND 1.36, Rhet. Herenn. 4.66, Quint. 5.11.23, 5.13.23); tectum and parietes are commonly combined from Cicero onwards (e.g. Verr. 5.184).

¹³³ In The Times for 20 January 1992 an article on informers in the former East Germany by the brilliant Bernard Levin was accompanied by a Peter Brookes cartoon depicting two apprehensive women walking alongside a wall which is topped with barbed wire and has grown a pair of very large ears. The conceit, albeit differently applied, also featured in numerous posters in World War II.