In Macbeth, a play by William Shakespeare, Banquo's soliloquy at the beginning of the third act explains some of his present feeling towards Macbeth. He believes that Macbeth killed to become the King of Scotland. He explains that he is the one who will start a chain of kings, not Macbeth. Strangely enough, Banquo makes this discovery two scenes from his death, not giving him enough time to tell others the discovery.
In the first three lines of the soliloquy, Banquo explains that Macbeth has become king just like the "weird women", or witches had prophesied. However, he also says that "thou play'dst most foully for't." Which basically means that he committed murder to attain it. He is Macbeth's best friend. He knows that Macbeth has the desire to be the king and would do anything to get the crown. Banquo knows Macbeth has it in him to commit murder.
In the next three lines, Banquo explains that he should really be the king because the witches also proclaimed that Banquo would be the "root and father of many kings." In the line, "May they not be my oracles as well and set me up in hope?", Banquo is saying that he wants the prophesies to come true for him also and make him the king and the beginning of a long line of kings.
The main idea of his soliloquy is that Banquo knows that Macbeth killed Duncan. Strangely enough, this soliloquy is placed two scenes before he died, not giving him enough time to tell anyone else about his discovery. Banquo has realized that Macbeth murdered Duncan but will die in two scenes anyway.
In Banquo's soliloquy in the beginning of the third act of Macbeth, Banquo suspects that Macbeth is behind Duncan's murder. He knows this because he has been best friends with Macbeth for a long time and knows that Macbeth has the ability to commit murder to get what he wants. Also, he believes that he should be next in line for the crown of Scotland because the "Weird Women", or witches proclaimed it to be true. He expresses that he wants to be the king .Oddly enough, Banquo is unable to share his theory on Duncan's murder with anyone else because he will be killed in two scenes, not giving him enough time.