Achilles was a Greek hero of the Trojan War and the central character and greatest warrior of Homer's Iliad. His mother was the immortal Thetis, and his father, the mortal King Peleus.
Achilles' most notable feat during the Trojan War was the slaying of the Trojan hero Hector outside the gates of Troy. Although the death of Achilles is not presented in the Iliad, other sources concur that he was killed near the end of the Trojan War by Paris, who shot him in the heel with an arrow. Achilles was invulnerable in all of his body except for his heel because, when his mother Thetis dipped him in the river Styx as an infant, she held him by one of his heels. Alluding to these legends, the term "Achilles heel" has come to mean a point of weakness, especially in someone or something with an otherwise strong constitution. The Achilles Instinct in men is then, the power and passion of knowing one's own weakness, even major handicaps, and developing strategies that capitalize on strengths, so as to make one's weaknesses relatively irrelevant. He is also the instinct in men that can turn enemies to friends.
Zeus and Poseidon had been rivals for the hand of Thetis until Prometheus warned Zeus of a prophecy that Thetis would bear a son greater than his father. For this reason, the two gods withdrew their pursuit, and had her wed Peleus.
According to the Iliad, Achilles arrived at Troy with 50 ships. When the Greeks left for the Trojan War, they accidentally stopped in Mysia, ruled by King Telephus. In doing battle with the inhabitants, Achilles gave Telephus a wound that would not heal, but when Telephus consulted an oracle who stated that "he that wounded shall heal", he sought after Achilles, who healed him so that he might become their guide for the voyage to Troy.
When Penthesilea, queen of the Amazons and daughter of Ares, arrives in Troy, Priam hopes that she defeat Achilles. After his temporary truce with Priam, Achilles fights and kills the warrior queen, only to grieve over her death later. At first, he was so distracted by her beauty, he did not fight as intensely as usual. Once he realized that his distraction was endangering his life, he refocused and killed her.
Achilles is then, also the instinct in men, not to be distracted from one's mission, to not give in to the Siren-like machinations of a female opponent, and to always place one's own mission above mere beauty and flirtation.
After his death, he meets Odysseus in the Underworld. Achilles asks Odysseus of his son's experiences in the Trojan war, and when Odysseus tells of the son's heroic actions, Achilles is filled with satisfaction. This gives us an ambiguous understanding of how Achilles felt about the heroic life. He is a "man's man."