At the start of the scene lady Macbeth appears to be confident in the acts she has caused. Little guilt or humanity appears to shine through and the only glimmer is when she speaks of being unable to carry out the act herself as the king resembed her father as he slept.
This revelation of her having some feelings deepens her character whereas before she is presentned as moral less and unaffected by the murder which will take place. This glimmer of humanity is alson foreshadowing events which will unfold later as her descwent into madness is caused by guilt and remorse.
The shreiking of the owl and chirping of the cricket symbolise the unbalance of nature after the unnatural deed is carried out. This idea is further developed in the later scene where there is talk of horses eating each other as a result of the king being murdered and nature being disturbed along with the natural order of events.
Macbeth is euphemistic about the…