, D 19
ταῦτα μὲν κτλ.
‘Yonder embellishments in the heavens, forasmuch as they are wrought in that which is seen with the bodily eye, we should indeed consider more beautiful and perfect than anything visible, but far inferior to those which are genuine and true—far inferior to the movements wherewith essential speed and essential slowness, in true and genuine number and in all true forms, are moved in relation to each other and therewithal make that which is essentially in them to move: the true adornments, which are apprehended by reasoning and the mathematical intelligence, but not by sight.’ The clause
κάλλιστα μὲν —ἔχειν is concessive, and
ἐπείπερ ἐν ὁρατῷ πεποίκιλται gives the reason why
τὰ ἐν οὐρανῷ ποικίλματα πολὺ ἐνδεῖ τῶν ἀληθινῶν (sc.
ποικιλμάτων), for the
ἀληθινὰ ποικίλματα are wrought, not
ἐν ὁρατῷ, but
ἐν νοητῷ, i.e. in the lower
νοητόν, with which and which alone the true astronomer as such is conversant. See App. I. The clause
ἃς τὸ ὀ=ν τάχος—φορὰς κτλ. explains
τῶν ἀληθινῶν (
ποικιλμάτων), being equivalent, as Schneider points out, to
τοῦτ’ ἔστι, τῶν φορῶν, ἂς κτλ., ‘that is, the movements which’ etc. So much for the relation between the different members of the sentence. In order to grasp the meaning of Plato, we should read the sentence aloud, letting the full stress of the voice fall on the words
ἀληθινῶν, ὄν, οὖσα, ἀληθινῷ, ἀληθέσι and
‐όντα in
τὰ ἐνόντα φέρει. Each of these words is emphatic, and expresses that degree of Truth or Being which belongs to the mathematical realities of true astronomy, as opposed to the sensibles or
αἰσθητά which form the subject-matter of the astronomy which Plato has just condemned. Popular astronomy observes with the bodily eye the movements of visible and material planets, e.g. Mercury and Mars. These two planets
φορὰς πρὸς ἄλληλα φέρει in
γιγνόμενος or
κινητὸς ἀριθμός, i.e. in time (cf.
Tim. 37 C
ff.), Mercury, as astronomers tell us, completing his orbit in about three, and Mars in about twenty-three, months. In the second place, these planets travel in
γιγνόμενα (not
ἀληθῆ)
σχήματα, i.e. in forms or orbits which belong to the world of
γιγνόμενα, and as they travel they carry with them the
γιγνόμενα which they contain, Mars for example his snow-caps and canals. The Platonic astronomer, on the other hand, looks with the eye of
διάνοια at the
ἀληθινὰ ποικίλματα, i.e. at the motions of true or mathematical stars. These mathematical stars
φορὰς πρὸς ἄλληλα φέρεται ἐν τῷ ἀληθινῷ ἀριθμῷ, i.e. in mathematical number, e.g. in 3 and 23 (not three
months, etc.), and also
ἐν ἀληθέσι σχήμασιν, i.e. in mathematical orbits, viz. the perfect ellipses which are imperfectly reproduced in the orbits of the visible material planets. Furthermore, although here perhaps our imagination may refuse to follow Plato in his flight, just as the visible Mars in his journey carries with him the
γιγνόμενα which he contains, so Plato represents the true stars of mathematical astronomy as carrying round with them
τὰ ἐνόντα, i.e. the mathematical
realities which are in them. The mathematical counterpart of Mars, for example, will take with it in its revolution those perfect mathematical forms which are imperfectly reproduced in the canals and snow-caps of the visible Mars. Plato in short conceives of a mathematical
οὐρανός of which the visible heavens are but a blurred and imperfect expression in time and space, just as every visible and material triangle is only an approximation to a true or perfect, i.e. a mathematical, triangle. The following remark of Aristotle's is intended as an objection to Plato's theory, but, according to the doctrine of this part of the
Republic, Plato would have accepted the criticism as containing a just and true account of the astronomy which he prescribes:
ἔτι δὲ εἴ τις παρὰ τὰ εἴδη καὶ τὰ αἰσθητὰ τὰ μεταξὺ θήσεται, πολλὰς ἀπορίας ἕξει. δῆλον γὰρ ὡς ὁμοίως γραμμαί τε παρ’ αὐτὰς καὶ τὰς αἰσθητὰς ἔσονται καὶ ἕκαστον τῶν ἄλλων γενῶν. ὥστ’ ἐπείπερ ἀστρολογία μία τούτων ἐστίν, ἔσται τις καὶ οὐρανὸς παρὰ τὸν αἰσθητὸν οὐρανὸν καὶ ἥλιός τε καὶ σελήνη καὶ τἄλλα ὁμοίως τὰ κατὰ τὸν οὐρανόν (
Met. B 2. 997^{b} 12 ff.). It remains to speak of two particular difficulties. What does Plato mean by
ταῦτα τὰ ἐν τῷ οὐρανῷ ποικίλματα, and by
τὸ ὂν τάχος καὶ ἡ οὖσα βραδυτής? The
ποικίλματα seem to be generally identified with the stars and nothing more. But inasmuch as astronomy deals with
φορὰ βάθους, and the ordinary astronomer, according to Plato, studies
τὰς τῶν ἄστρων φοράς (cf. 533 A) rather than
ἄστρα themselves, it may be presumed that the
ποικίλματα ἐν τῷ οὐρανῷ in reality denote the stars regarded as moving bodies, i.e., strictly speaking, the movements of the heavenly bodies revolving in their orbits (cf.
Tim. 39 D
and 40 C); and the presumption becomes a certainty when we reach the words
τῶν ἀληθινῶν, ἃς—φέρει, for since the true
ποικίλματα which true astronomy studies are identified with the movements of true stars, we are bound in like manner to suppose that the
γιγνόμενα ποικίλματα which observational astronomy studies are the movements of
γιγνόμενα ἄστρα. Some may be disposed to think that
τὰ ἐν οὐρανῷ ποικίλματα refers to the intricate and complex patterns which the orbits of the celestial bodies weave upon the Heavens: cf.
Tim. 39 D
τὰς τούτων πλάνας, πλήθει μὲν ἀμηχάνῳ χρωμένας, πεποικιλμένας δὲ θαυμαστῶς. But in view of expressions like
Aesch.
P. V. 24
ἡ ποικιλείμων νύξ and
Eur.
Hel. 1102
ἀστέρων ποικίλματα, it is better to hold that Plato adopts the word which was usually applied to the ‘spangles’ in the heavens, the “patines of bright gold,” with which “the floor of heaven is thick inlaid” (
Merchant of Venice V 1), and uses it of the movements of the stars, especially as throughout this chapter he consistently represents the visible stars which popular astronomy investigates as nothing but visible or material
φοραί. I understand
τὸ ὂν τάχος and
ἡ οὖσα βραδυτής as the mathematical counterparts of visible stars. This interpretation is, I think, the only one which gives a proper sense to
φοράς τε πρὸς ἄλληλα φέρεται καὶ τὰ ἐνόντα φέρει, and no other solution preserves in its full and unimpaired significance the necessary contrast between the astronomy of observation and Plato's form of the science. The place which in popular astronomy is occupied by a
γιγνόμενον τάχος, e.g. the planet Mercury, and a
γιγνομένη βραδυτής, e.g. the planet Mars, is in true astronomy filled by
ὂν τάχος and
οὖσα βραδυτής. Plato's conception of a true science of Astronomy is a remarkable product of his peculiar half-poetical, half-philosophical imaginative faculty, and differs fundamentally from the theory and practice of the science both in antiquity and now. But it must in fairness be allowed that if a science of astronomy could be constructed on Platonic principles, admitting no element of sense-perception, and dealing exclusively with incorporeal mathematical abstractions, it would prove a better prelude to the study of the
ἀχρώματός τε καὶ ἀσχημάτιστος καὶ ἀναφὴς οὐσία (
Phaedr. 247 C
) than could ever be provided by the astronomy which depends on observation of the heavenly bodies. See further App. II, and for other views of this passage App. X.