F1 Aetios III 17.3, p 383 Diels
(a) Stobaeus Anth [Ecl] 1.38: Πῶς ἀμπώτιδες γίνονται καὶ πλήμμυραι … Πυθέας ὁ Μασσαλιώτης τῇ πληρώσει τῆς σελήνης καὶ τῇ μειώσει τὰς ἑκατέρου τούτων αἰτίας ἀνατίθησιν …
How low and high tides are caused … Pytheas of Marseille attributes the causes of these to the waxing and waning of the moon.
(b) Ps-Plut 897b: Πῶς ἀμπώτιδες γίνονται καὶ πλήμμυραι … Πυθέας ὁ Μασσαλιώτης τῇ πληρώσει τῆς σελήνης τὰς πλημήρρας γίνεσθαι τῇ δὲ μειώσει τὰς ἀμπώτιδας.
How low and high tides are caused … Pytheas of Marseille [says that] high tides happen with the waxing moon and low tides at the waning moon.
Aetios, late 1st–early 2nd century AD, was the author of an encyclopedia or compendium summarising the views of philosophers on a range of scientific topics, called Collection of the Views of Natural Philosophers, or similar.1 The work is lost, but substantial citations survive. It is an invaluable source for many lost texts from Anaximander onwards,2 with the limitations of being summaries (hence the slightly different wording here), and usually from intermediate authors and not the original. Any modern discussion of tides states that they are caused by the gravitational pull of the moon and, to a lesser extent, the sun, with the rotation of the earth a third factor; the latter concept obviously unknown to Greeks. Aetios quotes ten opinions: three opted for the sun, three for the moon, and four variously proposed natural movements of the sea and rivers.3 Those who opted for the sun (Aristotle, Heraclides, Dicaiarchos) did so purely by inference,4 but those who posited the moon (Pytheas and Posidonios, and Seleucos of Seleucia for the Red Sea)5 must be credited with having made observations and intelligent deductions. This reference is also relevant for Pytheas’ route. Tides in the Mediterranean, with which Greeks were familiar, are modest; some call the Mediterranean tideless, though, as we see here, they had words for high and low tides. Pytheas could only have worked out the influence of the moon once in the Atlantic and saw that spring and neap tides corresponded to the phases of the moon. Posidonios seems to have based his observations at Cadiz (p xxi n 5). Pytheas’ book mentioned several tides: at Cape St Vincent (F34), around Britain (F5 and F16), and in the Baltic (F21, Appendix 4 §8, and see on F13).
F2 Cleomedes I 4 197–231 Todd
[197–208] λέγεται γοῦν ἐν Βρεττανίᾳ περὶ Καρκίνον τοῦ ἡλίου γινομένου καὶ τὴν μεγίστην ἡμέραν ποιοῦντος ὡς ὀκτὼ καὶ δέκα ὡρῶν ἰσημερινῶν γίνεται ἡ ἡμέρα, ἓξ δὲ ἡ νύξ· ὅθεν καὶ φῶς εἶναι παρ’ αὐτοῖς νυκτὸς κατὰ τὸν χρόνον τοῦτον, αὐτοῦ παρὰ τὸν ὁρίζοντα τοῦ ἡλίου παρατρέχοντος καὶ ἀποπέμποντος τὰς αὐγὰς ὑπὲρ γῆν· ὅπερ ἀμέλει καὶ παρ’ ἡμῖν γίνεται, ὅταν πελάσῃ τῷ ὁρίζοντι, πολὺ τοῦ φωτὸς τὴν ἀνατολὴν αὐτοῦ προλαμβάνοντος· ὅθεν καὶ ἐν Βρεττανίᾳ νυκτὸς εἶναι φῶς, ὡς καὶ ἀναγινώσκειν δύνασθαι. καὶ γὰρ τοῦτό φασιν ἀναγκαιότατον εἶναι, παρὰ τὸν ὁρίζοντα τοῦ ἡλίου τότε τὴν πορείαν ποιουμένου καὶ οὐ διὰ τῶν βαθυτέρων τῆς γῆς ἰόντος, διὰ τὸ ἐλάχιστον εἶναι παρ’ αὐτοῖς τμῆμα ὑπὸ γῆν τοῦ θερινοῦ κύκλου.
[209–231] περὶ δὲ τὴν Θούλην καλουμένην νῆσον, ἐν? γεγονέναι φασὶ Πυθέαν τὸν Μασσαλιώτην φιλόσοφον, ὅλον τὸν θερινὸν ὑπὲρ γῆς εἶναι λόγος, αὐτὸν καὶ ἀρκτικὸν γινόμενον αὐτοῖς. παρὰ τούτοις ὁπόταν ἐν Καρκίνῳ ὁ ἥλιος?, μηνιαία γενήσεται ἡ ἡμέρα, εἴ γε καὶ τὰ μέρη πάντα τοῦ Καρκίνου ἀειφανῆ ἐστι παρ’ αὐτοῖς, εἰ δὲ μή, ἐφ’ ὅσον ἐν τοῖς ἀειφανέσιν αὐτοῦ ὁ ἥλιός ἐστιν. ἀπὸ δὲ ταύτης τῆς νήσου προϊοῦσιν ὡς ἐπὶ τὰ ἀρκτικά, ἐκ τοῦ πρὸς λόγον καὶ ἕτερα μέρη πρὸς τῷ Καρκίνῳ γίνοιτ’ ἂν ἀειφανῆ τοῦ ζῳδιακοῦ. καὶ οὕτως, ἐφ’ ὅσον τὰ παρ’ ἑκάστοις φαινόμενα ὑπὲρ γῆς αὐτοῦ διέρχεται ὁ ἥλιος, ἡμέρα γενήσεται. καὶ ἔστι κλίματα τῆς γῆς ἀναγκαίως, ἐν οἷς καὶ διμηνιαία καὶ τριμηνιαία γίνεται ἡ ἡμέρα, καὶ τεσσάρων καὶ πέντε μηνῶν. ὑπὸ δὲ τὸν πόλον αὐτὸν ἕξ ζῳδίων ὑπὲρ γῆς ὄντων, ἐφ’ ὅσον ταῦτα διέρχεται ὁ ἥλιος ἀειφανῆ ὄντα, ἡμέρα γενήσεται, τοῦ αὐτοῦ κύκλου καὶ ὁρίζοντος καὶ ἀρκτικοῦ γινομένου αὐτοῖς καὶ ἰσημερινοῦ. τοῖς μὲν γὰρ ἐν Θούλῃ συμπίπτει ὁ θερινὸς τροπικὸς τῷ ἀρκτικῷ· τοῖς δ’ ἔτι ἐνδοτέρω ὑπερβαίνει ὁ ἀρκτικὸς τὸν θερινὸν εἰς τὰ πρὸς τὸν ἰσημερινὸν μέρη, ἐκ τοῦ πρὸς λόγον τούτου γινομένου· τοῖς δ’ ὑπ’ αὐτῷ τῷ πόλῳ ὁ ἰσημερινὸς τὰς τρεῖς λαμβάνει σχέσεις, ἀρκτικὸς μὲν γινόμενος, ὅτι περιλαμβάνει τὰ ἀειφανῆ τῶν ἄστρων μηδενὸς ἁπλῶς παρὰ ταύτοις ἢ δυομένου ἢ ἀνίσχοντος, ὁρίζων δὲ γίνεται, ὅτι χωρίζει τὸ ὑπὲρ γῆς τοῦ κόσμου ἡμισφαίριον ἀπὸ τοῦ ὑπὸ γῆν, ἰσημερινὸς δέ, ὅτι αὐτός ἐστιν ὁ διαιρῶν αὐτοῖς εἰς ἴσα τὴν ἡμέραν καὶ τὴν νύκτα, ὃς καὶ τοῖς ἄλλοις μὲν πᾶσιν ἐπ’ ἴσης ἰσημερινός ἐστιν, οὐκέτι δὲ οὔτε ὁρίζων οὔτε ἀρκτικός …
[197–208] So it is said that in Britain, when the sun is in Cancer and making the longest day, the day is about 18 equinoctial hours, and the night 6 hours; consequently there is light there at night during this time, since the sun runs along the horizon and sends its rays above the earth. This indeed also happens with us: when the sun approaches the horizon, much of its light anticipates its rising. So in Britain there is light at night, so that it is possible even to read. They say that this must necessarily be the case, because the sun makes its journey along the horizon and does not go through the deeper parts of the earth, because there the segment of the summer circle below the earth is very small.
[209–231] Around the island called Thule, where they say the philosopher Pytheas of Marseille was, it is reported that the whole of the summer [tropic] is above the earth, also becoming the arctic [circle] there. In this place, when the sun is in Cancer, the day will be a month long, at least if all parts of the Cancer are always visible to them; if not, for as long as the sun is in the parts of it [Cancer] that are always visible. As one goes further north from this island, by the same reasoning other parts of the zodiac will always be visible apart from Cancer. Therefore to the extent that the sun passes through what is visible [sc of the zodiac] above the earth in different places, there will be daylight. It necessarily follows that there are latitudes of the earth where the day lasts for two or three months, and four and five months. Since under the pole six signs of the zodiac are visible, as long as the sun goes through these ever visible signs, it will be daylight, since the same circle is the horizon, the arctic circle, and the equinoctial circle in this place. For those on Thule the summer [tropic] coincides with the arctic [circle]. For those further north, the arctic [circle] exceeds the summer [tropic] in proportion to the parts [of the heaven] approaching the equinoctial circle, in the same proportion. For those under the pole, the equinoctial [circle] takes on the three aspects: it is the arctic [circle], because it includes the stars which are always visible, with none of them ever either setting or rising; it is the horizon, because it separates the hemisphere above the earth from the one below it; and it is the equinoctial [circle], because it divides the day and night into equal parts; that is true elsewhere, but it is no longer either the horizon or the arctic [circle]….
Cleomedes, probable date c 200 AD, was a Stoic philosopher whose surviving work is a manual of astronomy called The Heavens or similar, thought to be based on a series of his lectures.1 It contains no original research, but is an important source for earlier thinking, including Posidonios (p xxi).2 Cleomedes has just said that the lengths of day and night differ at different latitudes because the sun passes through different parts of the zodiac circle; since this is at an angle to the observer’s horizon, some part of the zodiac is always below the earth at any given latitude.3