A bookshelf occupies a corner of a living room, its books shelved in alphabetical order by author's last name. Spines align evenly, creating a sequence recognized at a glance by regular viewers.
Books move in and out—removed for reading, returned to place, newcomers fitted into available spaces. The rows stay straight and full, preserving the expected look without interruption.
Selecting a volume reveals a change: books now form clusters by subject, with fiction beside fiction, history near history, science aligned separately. The author-based order vanishes.
The prior alphabetical lineup no longer structures the shelves; subject groupings take its place amid the same tidy display.
The bookshelf presents its volumes continuously, yet the arrangement resides now in subject clusters rather than author sequence, unmarked by any signal.