Note 15 — Chapter I

Plato was struck by the extreme difficulty of finding a standard in the human mind whereby we may test the truth or falsehood of spectral phenomena and dreams. And the only conclusion to which this consummate thinker could arrive, was that whatever appears true to the individual mind is true for him: which, however, is an evasion of the problem, not a solution of it. See the Theætetus, where Plato, as usual, puts his own speculations into the mouth of Socrates. He opens the question at the beginning of sec. 39 (Platonis Opera, vol. iii. p. 426, edit. Bekker, Lond. 1826), Μὴ τοίνυν ἀπολίπωμεν ὃσον ἐλλεῖπον αὐτοῦ. λείπεται δὲ ἐνυπνίων τε πέρι καὶ νόσων, τῶν τε ἄλλων καὶ μανίας, &c. These are the supposed sources of error; but Socrates, after discussing them, and entangling Theætetus in a maze, sums up at the end of sec. 45, p. 434, ἁληθὴς ᾰρα ἐμοὶ ἡ ἐμὴ αῐσθησις. See further, p. 515, on the formation of erroneous judgments; and respecting the assertions made by many of the Greeks that πᾶσα φαντασία ἀληθὴς and πᾶσα δύξα ἀληθὴς, compare Cudworth, vol. iii. p. 379, vol. iv. p. 118. For physiological considerations concerning the preservation of consciousness in dreams and in insanity, see Broussais, Examen des Doctrines Médicales, vol. i. p. 406; his Cours de Phrénologie, p. 49; Esquirol, Maladies Mentales, vol. i. p. 97, vol. ii. p. 790; Simon's Pathology, p. 204; Holland's Medical Notes, p. 434; Henle, Anatomie Générale, vol. ii. p. 287; Burdach, Traité de Physiologie, vol. v. p. 223. See, too, the passages in Tennemann which connect this difficulty with the theory of representation (Geschichte der Philosophie, vol. i. p. 357, vol. ii. pp. 119, 159, vol. iii. p. 406, vol. iv. p. 418); and the attempt of Berkeley (Works, vol. i. pp. 93, 101, 176) to turn it into a defence of his own system, on the ground that our belief respecting the external world may be as false when we are awake as when we dream. The solution offered by the Stoics is merely a verbal and unproved distinction: διαφέρει δὲ φαντασία καὶ φάντασμα. φάντασμα μὲν γάρ ἐστι δόκησις διανοίας οἴα γίνται κατὰ τοὺς ὔπνους⋅ φαντασία δέ ἐστι τύπωσις ἐν ψυχῇ τουτέστιν ἀλλοίωσις, ὡς ὁ Χρύσιππος ἐν τῇ δνωδεκάτη περὶ ψυῆς ὐφίσταται Diog. Laert. de Vitis Philos. lib. vii. segm. 50, vol. i. p. 395.