Metaphorically, a "Trojan horse" has come to mean any trick or stratagem that causes a target to invite a foe into a securely protected bastion or place.
The main ancient source for the story still extant is the Aeneid of Virgil, a Latin epic poem from the time of Augustus.
However, the god Poseidon sends two sea serpents to strangle him and his sons Antiphantes and Thymbraeus before any Trojan heeds his warning.
[8] In the Odyssey, Homer says that Helen of Troy also guesses the plot and tries to trick and uncover the Greek soldiers inside the horse by imitating the voices of their wives, and Anticlus attempts to answer, but Odysseus shuts his mouth with his hand.
[9] King Priam's daughter Cassandra, the soothsayer of Troy, insists that the horse will be the downfall of the city and its royal family.
[10] This incident is mentioned in the Odyssey: What a thing was this, too, which that mighty man wrought and endured in the carven horse, wherein all we chiefs of the Argives were sitting, bearing to the Trojans death and fate!
After many years have slipped by, the leaders of the Greeks, opposed by the Fates, and damaged by the war, build a horse of mountainous size, through Pallas's divine art, and weave planks of fir over its ribs they pretend it's a votive offering: this rumour spreads.
In Euripides' play Trojan Women, written in 415 BC, the god Poseidon proclaims: "For, from his home beneath Parnassus, Phocian Epeus, aided by the craft of Pallas, framed a horse to bear within its womb an armed host, and sent it within the battlements, fraught with death; whence in days to come men shall tell of 'the wooden horse,' with its hidden load of warriors.
"[14] It has been speculated that the story of the Trojan Horse resulted from later poets creatively misunderstanding an actual historical use of a siege engine at Troy.
Animal names are often used for military machinery, as with the Roman onager and various Bronze Age Assyrian siege engines which were often covered with dampened horse hides to protect against flaming arrows.
[19] This view has recently gained support from naval archaeology:[20][21] ancient text and images show that a Phoenician merchant ship type decorated with a horse head, called hippos ('horse') by Greeks, became very diffuse in the Levant area around the beginning of the 1st millennium BC and was used to trade precious metals and sometimes to pay tribute after the end of a war.
[26] A more speculative theory, originally proposed by Fritz Schachermeyr, is that the Trojan Horse is a metaphor for a destructive earthquake that damaged the walls of Troy and allowed the Greeks inside.
[31][32] Other early depictions are found on two relief pithoi from the Greek islands Mykonos and Tinos, both generally dated between 675 and 650 BC.
[35] An Attic red-figure fragment from a kalyx-krater dated to around 400 BC depicts the scene where the Greeks are climbing down the Trojan Horse, represented by the wooden hatch door.