In this paper we try to understand why Spinoza has attempted to redefine the mind as a spiritual automaton. As Descartes, author of the Ethics thinks that Thought and Extension, mind and body don't interact between themselves. However, against Descartes, he does not derive the ontological dualism from it, rather the ontological identity of the subject and the multiplicity of the attributes. On the basis of this ontological thesis, he defines the mind as a spiritual automaton. This shocking expression contains some innovative implications. First, it takes the mind not as a substrate in which the ideas are gathered together, but as a functional emsemble which thinks, feels, has affects and so on. Second, according to this conception, the cognition does not proceed from the things to the mind, but from one idea to another idea. Third, hence there is a proportional relation between action and passion of the mind, and action and passion of the body. Thus, Deleuze's reinterpretation of the parallelism is an interesting attempt to understand the novelty of Spinoza's conception of mind, but remains an insufficient one.