  In a previous publication, we introduced an abstract logic via an abstract
notion of quantifier. Drawing upon concepts from categorical logic, this
abstract logic interprets formulas from context as subobjects in a specific
category, e.g., Cartesian, regular, or coherent categories, Grothendieck, or
elementary toposes. We proposed an entailment system formulated as a sequent
calculus which we proved complete. Building on this foundation, our current
work explores model theory within abstract logic. More precisely, we generalize
one of the most important and powerful classical model theory methods, namely
the ultraproduct method, and show its fundamental theorem, i.e., Los's theorem.
The result is shown as independently as possible of a given quantifier.
