[127] Plat. Tim. p. 71 B-C. The criticism of Aristotle (De Partibus Animal. iv. 2, 676, b. 21) is directed against this doctrine, but without naming Plato. But when Aristotle says Οἱ λέγοντες τὴν φύσιν τῆς χολῆς αἰσθήσεως τινὸς εἶναι σημεῖον, οὐ καλῶς λέγουσιν, he substitutes the bile in place of the liver. In Aristotle’s mind the two are intimately associated.
Triplicity of the soul — espoused afterwards by Galen.
The Platonic doctrine, of three souls in one organism, derives a peculiar interest from the earnest way in which it is espoused afterwards by Galen. This last author represents Plato as agreeing in main doctrines with Hippokrates. He has composed nine distinct Dissertations or Books, for the purpose of upholding their joint doctrines. But the agreement which he shows between Hippokrates and Plato is very vague, and his own agreement with Plato is rather ethical than physiological. What is the essence of the three souls, and whether they are immortal or not, Galen leaves undecided:[128] but that there must be three distinct souls in each human body, and that the supposition of one soul only is an absurdity — he considers Plato to have positively demonstrated. He rejects the doctrine of Aristotle, Theophrastus, Poseidonius, and others, who acknowledged only one soul, lodged in the heart, but with distinct co-existent powers.[129]
[128] Galen, De Fœtuum Formatione, p. 701, Kühn. Περὶ Οὐσίας τῶν φυσικῶν δυνάμεων, p. 763. Περὶ τῶν τῆς ψυχῆς Ἠθῶν, p. 773.
[129] Galen, De Hipp. et Plat. Dogm. iii. pp. 337-347, Kühn, vi. pp. 515-516, i. p. 200, iv. p. 363, ix. p. 727.
Admiration of Galen for Plato — his agreement with Plato, and his dissension from Plato — his improved physiology.
So far Galen concurs with Plato. But he connects this triplicity of soul with a physiological theory of his own, which he professes to derive from, or at least to hold in common with, Hippokrates and Plato. Galen recognises three ἀρχὰς — principia, beginnings, originating and governing organs — in the body: the brain, which is the origin of all the nerves, both of sensation and motion: the heart, the origin of the arteries: the liver, the sanguifacient organ, and the origin of the veins which distribute nourishment to all parts of the body. These three are respectively the organs of the rational, the energetic, and the appetitive soul.[130]
[130] Galen, Hipp. et Plat. Dogm. viii. pp. 656-657, Kühn. ἐξ ὧν ἐπεραίνετο ἡ τῶν φλεβῶν ἀρχὴ τὸ ἧπαρ ὑπάρχειν· ᾧ πάλιν εἵπετο, καὶ τῆς κοινῆς πρὸς τὰ φυτὰ δυνάμεως ἀρχὴν εἶναι τοῦτο τὸ σπλάγχνον, ἥντινα δύναμιν ὁ Πλάτων ἐπιθυμητικὴν ὀνομάζει. Compare vi. 519-572, vii. 600-601.
The same triplicity of ἀρχαὶ in the organism had been recognised by Erasistratus, later than Aristotle, though long before Galen. Καὶ Ἐρασίστρατος δὲ ὡς ἀρχὰς καὶ στοιχεῖα ὅλου σώματος ὑποτιθέμενος τὴν τριπλοκίαν τῶν ἀγγείων, νεῦρα, καὶ φλέβας, καὶ ἀρτηρίας (Galen, T. iv. p. 375, ed. Basil). See Littré, Introduction aux Œuvres d’Hippocrate, T. i. p. 203.
Plato does not say, as Galen declares him to say, that the appetitive soul has its primary seat or ἀρχὴ in the liver. It has its seat between the diaphragm and the navel; the liver is placed in this region as an outlying fort, occupied by the rational soul, and used for the purpose of controuling the rebellious tendencies of the appetitive soul. Chrysippus (ap. Galen, Hipp. et Plat. Dogm. iii. p. 288, Kühn) stated Plato’s doctrine about the τριμερὴς ψυχὴ more simply and faithfully than Galen himself. Compare his words ib. viii. p. 651, vi. p. 519. Galen represents Plato as saying that nourishment is furnished by the stomach first to the liver, to be there made into blood and sent round the body through the veins (pp. 576-578). This is Galen’s own theory (De Usu Partium, iv. p. 268, Kühn), but it is not to be found in Plato. Whoever reads the Timæus, pp. 77-78, will see that Plato’s theory of the conversion of food into blood, and its transmission as blood through the veins, is altogether different. It is here that he propounds his singular hypothesis — the interior network of air and fire, and the oscillating ebb and flow of these intense agencies in the cavity of the abdomen. The liver has nothing to do with the process.