Physicality (Φ, the third structural condition of Nature, derived in its exchange role at [§2.4.8](<2.4.8 Exchange Requires Physicality.md>) and integrated into the Conditions-as-Nature sequence in [§2.6](<2.6 Triconditionality of Nature.md>)) is necessarily instantiated by the Necessity of Nature ([§2.8.5](<2.8.5 Necessity of Nature.md>)). Its quantity cannot pass through zero, because zero is not a value Substance can take: it is the absence of the bearer, and where the bearer fails, Physicality fails as a Condition. By the Necessity of Nature, Physicality cannot fail. Conservation, as such, is therefore not a contingent regularity Nature happens to exhibit. The fact that something persists (that Nature carries forward) is structural; the specific quantities conserved (energy, momentum, charge, baryon number) are what this universe's symmetries select to register that fact.

A second line arrives from Change. Exchange is one of the three constitutive requirements of Change ([§1.3](<1.3 Change.md>)), and exchange requires something to be exchanged. If no stock persisted across transitions, there would be nothing for succession to redistribute: only a series of disconnected states without the continuity that makes them a series at all. Succession needs exchange; exchange needs persisting relata; and the persisting relata are Substance, the bearer through which Physicality holds as a Condition. The two lines (instantiation from §[§2.4.8](<2.4.8 Exchange Requires Physicality.md>)–2.6 and exchange from [§1.3](<1.3 Change.md>)) converge on the same structural feature, which is again the overdetermination pattern §3 exploits.


---

← [7.4.2 What is Required](<7.4.2 What is Required.md>) | [7.4.4 What is Confirmed](<7.4.4 What is Confirmed.md>) →
