She had heard him, more than once, lock something up in one of the rooms—come out, and go into another room—wait there a few minutes—then return to the first room, with his keys in hand—and sharply turn the locks, and turn them again. […] [I]t was just as probable that these comings and goings, these lockings and unlockings, might be attributable to the existence of some private responsibility, which had unexpectedly intruded itself into the old man's easy existence, and which tormented him with a sense of oppression, new to the experience of his later years.
1862, [William] Wilkie Collins, chapter II, in No Name. […], volume III, London: Sampson Low, Son, & Co., […], 7th scene (St. Crux-in-the-Marsh), pages 254–255