Strength is power, vigour, solidity. It is the most that any one can achieve - pro virili in Latin. It is the effectiveness and worth of an action. Strength is preeminently a male characteristic, a compound of the undisputed superiority of male physical power, psychological strength and emotional stability. Strength is the characteristic of the victor, who decides things in his own right.
In the epic poems, and in tragedy, women attain heroic stature when they succeed, through torment and pain, in displaying understanding and endurance. Although the women of myth are prepared to take initiatives and confront situations with a large measure of hostility and anger - women like Penelope or Hecuba, for example - they are more often than not incapable of achieving any change in the flow of events.
On this matter, poetry seems in general to reflect the prevailing ideology, as crystallised in the funeral oration of Perikles:
Thucydides II, 45 (Loeb edition)
Thus, the very few women in myth who possess strength transcend their female nature. They display a physical power that is made public through athletic competition, hunting, or prowess in war, and may also possess the intellectual and psychological strength to take decisions and then act upon them. In both cases, their gift ultimately turns into a monster since it is contrary to the female nature, as it had been defined.
The woman who possesses strength is dangerous. Her unnatural power is explained in terms of her being a foreigner, a barbarian, like the Amazons. She is a foreigner, a barbarian and a witch, like Medea and Cassandra. She is beautiful beyond reason and can therefore bring about disaster, like Helen. She is an athlete, a huntress and shuns the marriage bed, conquering and killing any aspiring suitors, like Atalanta.
Women who complain about their sufferings, and even more so women who protest about the role assigned to them in life, are presented as negative values - they are the 'evil women' of epic poetry and tragedy, women like Clytaemnestra, Deianeira or, again, Medea.
And herein lies the contradiction: in their efforts to preserve their human dignity, which has been wounded, these characters decide to take action. Their action leads them out of the dungeon of waiting and expectation, but at the same time results in their expulsion from the 'tribe of women'.
Aeschylus, Agamemnon 1426-1430 (Loeb edition)
From Medea to Sappho - Radical Women in Ancient Greece
Athens, National Archaeological Museum - 20 March - 30 June 1995