Remember there was considerable controversy over the exact meaning of the Homeric term πεῖραρ. 'Rope' seemed a natural reading but exegetes puzzled over the range of meanings which included 'boundary' or 'end.'Socrates: Need I speak further of such things as stagnation in air and water, where stillness causes corruption and decay, when motion would keep things fresh, or to complete the argument, press into service that 'golden rope' in Homer, proving that he means by it nothing more nor less than the sun, and signifies that so long as the heavens and the sun continue to move round, all things in heaven and earth are kept going, whereas if they were bound down and brought to a standstill, all things would be destroyed and the world, as they say, turned upside down?
To this end it is interesting that just as Plato argued that 'the golden rope' was really a harmony the same line of reasoning is developed in Against Marcion 4. The book opens:
The puzzling use of 'instrumentum' in Tertullian has never been explained. But interestingly one of the meanings of πεῖραρ is 'instrument':Besides that, to work up credence for it [gospel] he has contrived a sort of dowry, a work entitled Antitheses because of its juxtaposition of opposites, a work strained into making such a division between the Law and the Gospel as thereby to make two separate gods, opposite to each other, one belonging to one instrument (or, as it is more usual to say, testament), one to the other, and thus lend its patronage to faith in another gospel, that according to the Antitheses.
Could this be the clue to solve the mystery of the over-arching point of the book? Namely that Marcion is arguing for two πείρατα - one for the gospel and another for the law - whereas the correct understanding according to the author is that there is one πεῖραρ which 'harmonizes' between the tensions in the two texts.πεῖραρ (also πεῖρας , v. infr. 1.5), α^τος, τό, Ep., Ion., and Lyr. form of πέρας,
A.end, limit, “οὐδ᾽ εἴ κε τὰ νείατα πείραθ᾽ ἵκηαι γαίης καὶ πόντοιο” Il. 8.478, cf. Od. 5.463, 11.13.
2. completion, οὐ γάρ πω πάντων ἐπὶ πείρατ᾽ ἀέλων ἤλθομεν the end of our labours, 23.248.
3. achievement, execution, mode or means of execution, “ᾧ παιδὶ ἑκάστου πείρατ᾽ ἔειπε” Il.23.350 ; “πείρατ᾽ ἀέθλων δείκνυεν” Pi. P.4.220 ; εἰ δέ τις ἀνδρῶν ἡμετέρης τέχνης πείρατά φησιν ἔχειν says he possesses the secret ( = power of execution) of my art, Zeuxisin PLG2.318, cf. IG 3.399 ; νίκης πείρατ᾽ ἔχονται ἐν ἀθανάτοισι θεοῖσι the achievement of victory is dependent on the gods, Il. 7.102 ; “νίκης ἐν θεοῖσι πείρατα” Archil. 55.
4. final decision, verdict, “ἐπὶ ἴστορι πεῖραρ ἑλέσθαι” Il.18.501.
5. doom, “ἐκφυγέειν μέγα π. ὀϊζύος” Od.5.289 ; “ὥς κεν θᾶσσον ὀλέθρου πείραθ᾽ ἵκηαι” Il.6.143 ; “πεῖρας θανάτου” Pi.O.2.31.
II. instrument, tool, “ἦλθε δὲ χαλκεὺς ὅπλ᾽ ἐν χερσὶν ἔχων χαλκήϊα, πείρατα τέχνης, ἄκμονά τε σφῦράν τ᾽ εὐποίητόν τε πυράγρην” Od.3.433, cf. Sch. Dad loc.
2. esp. tackle, rope, “δησάντων σ᾽. . ὀρθὸν ἐν ἱστοπέδῃ, ἐκ δ᾽ αὐτοῦ πείρατ᾽ ἀνήφθω” Od.12.51 ; “οὐδ᾽ ἔτι δεσμά σ᾽ ἔρυκε, λύοντο δὲ πείρατα πάντα” h.Ap. 129 : metaph., “πτολέμοιο πεῖραρ . . τάνυσσαν” Il.13.359 : “Τρώεσσιν ὀλέθρου πείρατ᾽ ἐφῆπται” 7.402 ; “πᾶσιν ὀλέθρου πείρατ᾽ ἐφῆπτο” Od. 22.33 ; “καιρὸν εἰ φθέγξαιο, πολλῶν πείρατα συντανύσαις ἐν βραχεῖ” Pi.P.1.81. (περ-Fṛ-, περ-Fṇ-τ-, cogn. with πείρω, πόρος.)