[Sidenote: The double immortality, past and future.] Thus Plato's doctrine of the immortality of the soul implies a double immortality; the past eternity, as well as that to come, falls within its scope. In the national superstition of his time, the spiritual principle seemed to arise without author or generator, finding its chance residence in the tabernacle of the body, growing with its growth and strengthening with its strength, acquiring for each period of life a correspondence of form and of feature with its companion the body, successively assuming the appearance of the infant, the youth, the adult, the white-bearded patriarch. The shade who wandered in the Stygian fields, or stood before the tribunal of Minos to receive his doom, was thought to correspond in aspect with the aspect of the body at death. It was thus that Ulysses recognized the forms of Patroclus and Achilles, and other heroes of the ten years' siege; it was thus that the peasant recognized the ghost of his enemy or friend. As a matter of superstition, these notions had their use, but in a philosophical sense it is impossible to conceive anything more defective. [Sidenote: Relations of the past and future to man.] Man differs from a lifeless body or a brute in this, that it is not with the present moment alone that he has to deal. For the brute the past, when gone, is clean gone for ever; and the future, before it approaches, is as if it were never to be. Man, by his recollection, makes the past a part of the present, and his foreknowledge adds the future thereto, thereby uniting the three in one. [Sidenote: Criticism on the Ideal theory.]