 In later works the specificity of ontology was quickly dissolved into logic on the one hand (an abstract science which shares with ontology the same principle of non-contradiction, see VS 52–55) and into rational theology on the other hand, the science of immaterial beings and first causes. This dissolution may be seen as anticipating Descartes’s own reduction of metaphysics to “prime philosophy”, and, according to Marion, this is a very significant (albeit a merely negative one) legacy of Mersenne’s work to the history of metaphysics.