Before the 1890s, most offices stored correspondence in bound letter-books or flat document boxes, both of which required roughly linear, chronological retrieval — find the right volume, then hunt page by page. The vertical filing cabinet, popularised at the 1893 World's Columbian Exposition, replaced that with hanging folders addressable directly by name or subject, retrievable in seconds rather than minutes. It was, in every meaningful sense, a random-access upgrade to an office's storage medium.
Random access before the term existed
Computer scientists would later use "random access" to describe memory that can be read in any order, without paging sequentially through everything before it. The vertical file cabinet delivered exactly that improvement to paper: any folder retrievable directly, without paging through the ones filed before it. Office productivity guides of the era described the shift in almost identical terms to how a technology journalist might describe an upgrade from tape storage to disk.
What got lost in the upgrade
The bound letter-book had one accidental virtue the filing cabinet gave up: an unbreakable chronological sequence, since pages couldn't be removed or reordered without visible damage. The filing cabinet's folders could be reordered, misfiled, or quietly removed, trading tamper-evidence for speed — the identical trade-off a modern system makes when it moves from an append-only log to a directly editable record.
Every leap in retrieval speed quietly gives something up. The filing cabinet's real innovation was deciding that speed was worth more than sequence.
The database index and the manila folder are separated mostly by material, not by idea.