Plato's thought on the question of the immortality of the soul, in the sense of the existence after death of an individual personality, is stated by Constantin Ritter in his book on The Essence of Plato's Philosophy as follows: “I must admit that for Plato personal immortality was a serious problem and that his whole exposition and especially the trend of his argument in the Phaedo, urges us to accept it” (page 119); and again—“The notion of immortality in the sense that we understand it, viz. the survival of personality beyond the limits of earthly existence, was for Plato a serious problem; but it never became a dogma with him, even though he gives us a strong hint in the Phaedo to affirm this notion” (page 301).