Descartes has still not given proof that such external objects exist. At this point, he has only shown that their existence could conveniently explain this mental process. To obtain this proof, he first reviews his premises for the "Meditations"—that the senses cannot be trusted and what he is taught "by nature" does not have much credence. However, he views these arguments within a new context; after writing "Meditation I", he has proved the existence of himself and of a perfect God. Thus, Descartes jumps quickly to proofs of the division between the body and mind and that material things exist: