Soliloquy- A person alone on stage speaking whats on his mind"I have no spur/
To prick the sides of my intent, but only/
Vaulting ambition"
This reason Macbeth is killing Duncan is selfish. He wants to kill Duncan so that he can be king it's not for any ones good but his. Duncan is a loved king he does things for the good of others There is no other reason for Macbeth to want kill him just for his own selfish reasons.
