We carry out some of Galois' work in the setting of an arbitrary
first-order theory T. We replace the ambient algebraically closed
field by a large model ℳ of T, replace fields by definably
closed subsets of ℳ, assume that T codes finite sets, and obtain
the fundamental duality of Galois theory matching subgroups of the
Galois group of L over F with intermediate extensions F ≤
K ≤ L. This exposition of a special case of [10] has
the advantage of requiring almost no background beyond familiarity
with fields, polynomials, first-order formulae, and automorphisms.