We reconsider differential geometry from the point of view of the quan
tum theory of non-relativistic spinning particles, which provides exam
ples of supersymmetric quantum mechanics. This enables us to encode ge
ometrical structure in algebraic data consisting of an algebra of func
tions on a manifold and a family of supersymmetry generators represent
ed on a Hilbert space. We show that known types of differential geomet
ry can be classified in terms of the supersymmetries they exhibit. Our
formulation is tailor-made for a generalization to non-commutative ge
ometry, which will be presented in a separate paper.