Solipsism then they must be identical, as in indistinguishable from each other and therefore one and the same thing. Dualists then attempt to identify attributes of mind that are lacked by matter (such as privacy or intentionality) or vice versa (such as having a certain temperature or electrical charge). One notable application of the identity of indiscernibles was by René Descartes in his "Meditations on First Philosophy". Descartes concluded that he could not doubt the existence of "himself" (the famous "cogito ergo sum" argument), but that he "could" doubt the (separate) existence of "his" body. From this, he inferred that the
Mr. Cogito whose presence is introduced by a poem entitled "Dusza Pana Cogito" (Mr. Cogito's Soul). It brings to our attention Mr Cogito's soul leading a life of its own. In contrast with the souls of the ancient world, it tends to leave him unexpectedly, wandering here and there, oblivious of the owner's well-being. The soul always returns, though, making it possible for Mr. Cogito to adore the world's beauty and diversity in the next poem – "Modlitwa Pana Cogito – podróżnika" ("A Prayer Of Mr. Cogito The Traveller"). This is followed by "Pan Cogito – powrót" ("Mr. Cogito – A Return"),