  Discussed here is descent theory in the differential context where everything
is equipped with a differential operator. To answer a question personally posed
by A. Pianzola, we determine all twisted forms of the differential Lie algebras
over $\mathbb{C}(t)$ associated with complex simple Lie algebras. Hopf-Galois
Theory, a ring-theoretic counterpart of theory of torsors for group schemes,
plays a role when we grasp the above-mentioned twisted forms from torsors.
