Let 𝒜 be a finite-dim transitive Lie algebra of vector field germs at $0\in \R^n$ and let ℐ be its isotropy subalgebra. When ℐ is diffeomorphic to the isotropy representation j1ℐ (i.e. can be linearized)? I will discuss this question from various points of view and will formulate and explain some unexpected theorems.