The opening lines of the Philoctetes. Here's Jebb's translation:
This is the headland of sea-washed Lemnos, land untrodden by men and desolate. It was here, child bred of the man who was the noblest of the Greeks, Neoptolemus son of Achilles, that I exposed long ago the native of Malis, Poeas' son, on the express command of the two chieftains to do so, because his foot was all running with a gnawing disease.
The first word of a work of Sophocles often is worth attending to. Here it's ἀκτὴ:
ἀκτή (A), ἡ,
A. headland, foreland, promontory,
2. generally, tract of land running out into the sea,
II. generally, edge,
From the vantage point of a sailor or a drowning man, a headland or promontory is the prospect of salvation.
From the perspective of a stranded Crusoe figure, the point where land runs out to the sea is the limit of one's motion -- the isolating (isola = island) wall or threshold of one's world.
The ἀκτή can be the hoped-for, salvational terra firma, or a limiting wall of despair, depending on whether one is drowning at sea or attempting to escape a deserted (οὐδ᾽ οἰκουμένη) island. That is to say, the edge cuts both ways - it's liminal.
We are at the edge of the text. Odysseus is speaking, introducing Neoptolemus and us to the scene. He begins with ἀκτή and moves through a concise statement of how he, Odysseus, isolated Philoctetes here under the orders of the Atreidai, before he ends at Philoctetes' dripping (καταστάζοντα) foot. Another edge, suppurating flesh and liquid mixed - a shedding wound upon which the serpent-bitten man cannot stand, move, or rest.
In a play that is deeply about separation, about a vast interwoven story of two nations and the isolated individual who yet is necessary to the resolution of their conflict, the question of edges, borders, limits is basic. Consider the moments in the play in which edges appear to disappear. One example might be the central choral ode in which the singers, taking part in Odysseus's plot to trick Philoctetes, are moved by the subject of their song -- the wounded man's plight. Another might be the moment Philoctetes set fire to Heracles' funeral pyre -- where the hero's suffering body, consumed in fire, ceased to suffer and, the tales tell, began another journey.
From its first word, the Philoctetes is grappling with edges -- encountering the nature of their limits, discovering that they can be suspended, crossed, transcended. Sophocles gives us much to attend to.