Basil L. Gildersleeve, Syntax of Classical Greek

I. As a general rule when the name of a river is mentioned for the first time, the type “ὁ Νεῖλος” is used of well-known rivers, the type “ὁ Στρυμὼν ποταμός” of fairly well-known rivers, and the type “Βρόγγος ποταμός” or “ποταμὸς Βρόγγος” of obscure rivers.

“τοῦ Νείλου”, HDT.2.10. “οἳ δὲ . . . ἔφραζον ὡς . . . εἴη . . . ἡ Παιονίη ἐπὶ τῷ Στρυμόνι ποταμῷ πεπολισμένη”HDT., 5.13. “ἐξ Ἰλλυριῶν δὲ ῥέων . . . Ἄγγρος ποταμὸς ἐσβάλλει . . . ἐς ποταμὸν Βρόγγον”HDT., 4.49.

II. When a river that has once been mentioned is referred to again by name in the same context, the article is used with the second name, but to this in the case of obscure rivers the word “ποταμός” is generally attached.

“κατὰ τὸν Νεῖλον”, HDT.2.10 follows “τοῦ Νείλου” mentioned a few lines preceding. “ἐπὶ τῷ Στρυμόνι ποταμῷ . . . ὁ δὲ Στρυμών”, HDT.5.13. “ἐς ποταμὸν Βρόγγον, ο: δὲ Βρόγγος”, HDT.4.49. “κατήκοντες ἐπὶ ποταμὸν τῷ οὔνομα κέεται Παντικάπης”, HDT.4.18; but “διαβάντι τὸν Παντικάπην ποταμόν”, Ibid. 19.

III. All rivers are anarthrous and are sometimes accompanied by the word “ποταμός”

I. In the predicate.

“τὸν δὲ δὴ ποταμὸν τοῦτον . . . συνεβάλλετο εἶναι Νεῖλον”, HDT.2.33.

2. In enumerations.

“ἄλλοι μεγάλοι . . . ἐσβάλλουσι ἐς αὐτόν, Ἄτλας καὶ Αὔρας καὶ Τίβισις. διὰ δὲ Θρηίκης . . . ῥέοντες Ἄθρυς καὶ Νόης καὶ Ἀρτάνης ἐκδιδοῦσι ἐς τὸν Ἴστρον”, HDT.4.49.

3. In dependence upon the word “πεδίον”.

“ἐν Μαιάνδρου πεδίῳ”, HDT.1.18.

4. In attributive prepositional phrases; with improper prepositions; in the phrase “ἀπὸ . . . ἐς, ἐπί, μέχρι”; and in double designations of locality.

“τῇ ἐπὶ Θερμώδοντι μάχῃ”, HDT.4.110. “μέχρι Ἴστρου ποταμοῦ”, HDT.4.89. “ἀπὸ γὰρ Ἴστρου ἐπὶ Βορυσθένεα”, HDT.4.101. “αὐτοῦ περὶ Ἄξιον ποταμὸν καὶ πόλιν Θέρμην”, HDT.7.124（“Ἄξιος” already mentioned in 123).

5. When the name is emphatically placed at the head of the sentence.

“Νείλου μέν νυν πέρι τοσαῦτα εἰρήσθω”, HDT.2.35.

6. When an articular attributive expression is attached to the name.

“Νεῖλός τε ὁ Αἰγύπτιος ποταμὸς . . . καὶ Φᾶσις ὁ Κόλχος”, HDT.4.45. “πλὴν Νείλου τοῦ Αἰγυπτίου”, Ibid. 53.¹

DEM. [59]DEM., 99: “ὁ γὰρ Ἀσωπὸς ποταμὸς μέγας ἐρρύη”.

AESCHIN.2.124: “εἰσπλεῖν μέ φησιν . . . κατὰ τὸν Λοιδίαν ποταμόν. 3.183: ἐπὶ τῷ Στρυμόνι ποταμῷ ἐνίκων μαχόμενοι Μήδους”.

ISOC.4.144: “τῆς ἐντὸς Ἅλυος χώρας. 7.80: ἐντὸς Ἅλυος ποταμοῦ. 11.12: τῷ Νείλῳ. 31: τὸν . . . Νεῖλον τερὶ τὴν χώραν περιέρρηξε. 12.59: ἐντὸς Ἅλυος”.

PLATO, Phaedr. 229A: “δεῦρ᾽ ἐκτραπόμενοι κατὰ τὸν Ἰλισσὸν ἴωμεν”. 257 E: “τοῦ μακροῦ ἀγκῶνος τοῦ κατὰ Νεῖλον”. But Politic. 264 C: “ταῖς ἐν τῷ Νείλῳ τιθασείαις τῶν ἰχθύων καὶ τῶν ἐν ταῖς βασιλικαῖς λίμναις”. Tim. 21 E: “τὸ τοῦ Νείλου ῥεῦμα”.

In the Anabasis “ποταμός” is regularly added to the articular name, and even the most obscure rivers often take the article, but the following rule is observed: In introducing a comparatively unknown river, Xenophon uses the article when narrating the march of his own army, but omits it in merely geographical descriptions. 1.2.11: “εἰς Καΰστρου πεδίον. 1.4.1: ἐξελαύνει . . . ἐπὶ τὸν Πύραμον ποταμόν. 2.5.1: ἀφικνοῦνται ἐπὶ τὸν Ζαπάταν ποταμόν. 5.3.8: ἔτυχε δὲ διαρρέων . . . ποταμὸς Σελινοῦς. καὶ ἐν Ἐφέσῳ δὲ . . . Σελινοῦς ποταμὸς παραρρεῖ. 5.6. 36: πλεῖν εἰς Φᾶσιν” and so regularly because the name of the city is included. 7.8.8: “εἰς Και:´κου πεδίον”.

In the Hellenica the articular name without “ποταμός” is more commonly used, the rivers of the Hellenica being for the most part well known. So the Alpheus, Eurotas, Attic and Boeotian Cephisus, and the Maeander. In the case of the Eurymedon, the Pactolus, and the Cladaus, the articular name is followed by “ποταμός”. See Kallenberg, l.c., p. 11.

THUCYDIDES in general follows the same rules as Herodotus, but for obvious reasons the anarthrous name with “ποταμός” is much less common than in Herodotus. The names of insignificant rivers of Sicily and Lower Italy, which had become familiar to the Athenians as a result of the Sicilian expedition, follow the type “ὁ Ἀχελῷος ποταμός. 1.46.4: διὰ δὲ τῆς Θεσπρωτίδος Ἀχέρων ποταμὸς ῥέων . . . ῥεῖ δὲ καὶ Θύαμις ποταμός. 98.1: Ἠιόνα τὴν ἐπὶ Στρυμόνι. 100.1: ἡ ἐπ᾽ Εὐρυμέδοντι ποταμῷ . . . πεζομαχία. 100.3: ἐπὶ δὲ Στρυμόνα” (omission of the article exceptional) “πέμψαντες . . . οἰκήτορας. 2.5.2: ὁ γὰρ Ἀσωπὸς ποταμός. 96.3: μέχρι . . . τοῦ Στρυμόνος ποταμοῦ” (but 2.97.2. 4.102.4. 108.1. 6. 5.7.4. 7.9, with the article alone). 2.96.4: “μέχρι τοῦ Ὀσκίου ποταμοῦ”. (The Oscius had become so familiar to Thucydides that he unwittingly presupposes general acquaintance with the river on the part of the Athenians.) 97.1: “μέχρι Ἴστρου ποταμοῦ . . . ἐξ Ἀβδήρων ἐς Ἴστρον. 99.4: πέραν Ἀξίου μέχρι Στρυμόνος. 102.2: ὁ γὰρ Ἀχελῷος ποταμός” (but ibid. 3. 3.7.4. 106.1 without “ποταμός”). 3.19.2: “διὰ τοῦ Μαιάνδρου πεδίου. 6.4.1: ὑπὲρ Παντακύου . . . ποταμοῦ. 7.80.5: ὅπως ἐπειδὴ γένοιντο ἐπὶ τῷ ποταμῷ τῷ Κακυπάρει, παρὰ τὸν ποταμὸν ἴοιεν ἄνω διὰ μεσογείας” (“τῷ ποταμῷ” gloss?). 7.82.3: “ἀφικνοῦνται ἐπὶ τὸν ποταμὸν τὸν Ἐρινεόν” (“τὸν ποταμόν” gloss?). 8.58.1: “ἐν Μαιάνδρου πεδίῳ”.

For Herodotus, see the boldface examples above and Kallenberg, l.c.