Only for them, and mine eternal jewel Given to the common enemy of man, To make them kings, the seed of Banquo kings!" mean in Macbeth?
In the play "Macbeth", the phrase "Only for them, and mine eternal jewel Given to the common enemy of man, To make them kings, the seed of Banquo kings!" reflects Macbeth's deep frustration and regret. He laments that he sacrificed his salvation and committed regicide only to ensure the kingship of Banquo's descendants. This realization leads to bitterness, resentment, and further tyranny as he seeks to eliminate Banquo's line, marking his transformation from an ambitious man to a spiteful monster.
Therefore, as he thinks back on the witches' prophecy that Banquo's descendants will inherit Scotland's throne, he becomes bitter. He says "only for them," meaning by "them" Banquo's heirs, contemptuously, now realizing it was hardly worth it to sacrifice his "eternal jewel"—his salvation in heaven—so that Banquo's line could be kings. Since being king in the present moment is no fun and brings Macbeth no fulfillment, he seethes with anger that his work may "make . . . the seed of Banquo kings!" We can almost feel him gnashing his teeth and wanting to lash out at someone in his pain.Macbeth is saying he has sold his soul (his eternal jewel) to the devil (the common enemy of man), but he cannot bring himself to say as much in plain words because he doesn't even want to think about that terrible truth.