How does shakespeare’s use of the specific simile “i am constant as the northern star” support the statements he makes in the rest of his speech?

caesar says that he’s constant like the northern star but that he can change his mind depending on what other men say or do.
caesar says that he is never set like the northern star, but instead, he likes to change his mind and actions just like other men do.
caesar says that he’s as constant as the northern star set in the sky, and he talks about the ways he differs from other men by being constant.
caesar says that he’s not set like the northern star, and he talks about the ways he is like other men by being constant.