Reverse Causality Stacks

The Reverse Causality Stacks are a closed collection of shelving ranges maintained on Floor Δ-19 for the safe keeping of documents whose effects have already been recorded but whose contents have not yet been written. They are administered jointly by the Department of Material Causality and the Ambient Causality Observatory of Spiral 88, an arrangement that has produced four centuries of procedural friction and no measurable improvement in retrieval times. The Stacks hold an estimated 41,000 volumes, of which 2,300 have been read. The remainder are catalogued as pending inscription.

Unlike Reverse Temporal Causality, which concerns events and is monitored under the Concordance of Reverse Precedents, the Stacks concern documents alone. A volume enters the Stacks when a citation to it is found in a record dated before the volume's own accession. The volume is then shelved at the position its citation implies and left there until an archivist writes it.

Doctrine of the Pending Volume

The governing doctrine is set out in Annex γ-9 of the Concordance of Reverse Precedents, which distinguishes between a document that has been written and one that has been required. The distinction is preserved chiefly by the practice of shelving uninscribed volumes spine-inward, so that a reader approaching the range is shown the back of a book whose title does not yet exist. Librarians are instructed not to speculate about the contents of pending volumes while within sight of them.

"A pending volume may be cited, weighed, and rebound. It may not be summarised, not even provisionally, and not even to oneself while shelving."

— Concordance of Reverse Precedents, Annex γ-9, clause 4

The Bureau of Spatial and Temporal Alignment classifies entries to the Stacks under the same three categories it applies to Reverse Temporal Causality generally, though the Bureau has twice declined to say which category the Stacks themselves occupy. This hesitation is recorded in Determination 188 without comment.

The Vel Accession

The modern form of the Stacks owes much to P. Vel, who in the winter of the year recorded as 3112 filed a run of Type Δ cases — among them the reverse-temporal matter and the affair of the Immutable Mobile — that required the shelving of volumes whose citations preceded them by as much as ninety years. Vel's grievance, entered in the margin of a finding now bound into Temporal Resolutions, was that the existing ranges had no bay deep enough for a book that had been cited but not written and whose future author had not yet been born. The Department of Material Causality answered that this was a matter of shelf depth and not of doctrine, and widened the ranges by eleven centimetres.

The Department has maintained the eleven-centimetre allowance ever since. It is checked at each restoration cycle with a brass gauge kept in the range-master's desk, and volumes found to exceed the allowance are shelved in the annex to the annex, which is not on any plan.

Dispute over Sequence

Whether the Stacks should be ordered by accession or by the date of their earliest citation remains unresolved. The Department of Material Causality holds that accession order is the only order a shelf can bear. The Observatory holds that a shelf ordered by accession is a shelf lying to the reader, and cites the Principle of Sequential Indeterminacy in support. The Principle of Insufficient Causality has been raised by both parties, each time against the other.

The dispute was referred to the Chamber of Conditional Causality in the year recorded as 3387 and returned unopened, with a note that the question had already been settled in a judgment the Chamber had not yet been asked to give.

Finding Aids

The Stacks are served by the Reverse Index, use of which is required in all matters touching Reverse Temporal Causality. Entries are keyed to the citation that called the volume into being rather than to the volume itself, so that a reader searching for a title will find only the records that will one day require it.

Retrieval is by written request. The ranges are unlit between the hours of shift-change, and no reader may descend the eastern stair while carrying an unwritten volume, a rule introduced after the retrograde incident of the year recorded as 3401 and never explained in the standing orders.

The Concordance of Reverse Precedents remains the primary procedural manual for all agencies monitoring Reverse Temporal Causality, and the Stacks are accordingly inspected, but no inspection has ever reported a discrepancy, since a discrepancy would require the inspector to compare a written record with an unwritten one. The Tower has no procedure for this, and no floor has requested one.