  Since 1883, Picard-Vessiot theory had been developed as the Galois theory of
differential field extensions associated to linear differential equations.
Inspired by categorical Galois theory of Janelidze, and by using novel methods
of precategorical descent applied to algebraic-geometric situations, we develop
a Galois theory that applies to morphisms of differential schemes, and vastly
generalises the linear Picard-Vessiot theory, as well as the strongly normal
theory of Kolchin.
