Brownian motion in Euclidean space; Diffusions in Euclidean space; Some addenda, extensions, and refinements; Doing it on a manifold, an extrinsic approach; More about extrinsic Riemannian geometry; Bochner's identity; Some intrinsic Riemannian geometry; The bundle of orthonormal frames; Local analysis of Brownian motion; Perturbing Brownian paths.