How does Shakespeare's interest in human nature refers to Macbeth?
Shakespeare's plays can indeed be viewed as studies of human nature and human behavior. The main characters of his plays (his heroes and heroines) are very complex characters, and their complexity can often be seen in the soliloquies.
Macbeth is a study of the corruption of human nature. The transformation of our tragic hero Macbeth from a valiant and loyal fighter to an evil and cold-blooded murderer is a striking one. Shakespeare delves deep into human nature and explores Macbeth's hidden desires and ambitions. We realize that Macbeth's tragic flaw is his unrestrained ambition which makes him commit various atrocious acts like killing the king of Scotland and many other innocent people.
Nevertheless, Shakespeare is also great at showing us the complexity of human nature. Although Macbeth accepts evil and wants to reject the goodness inside him, we see traces of his guilt-ridden conscience, manifested in his hallucinations. In addition, his soliloquies reveal that he has many doubts and fears, so to view him only in terms of the crimes he committed would be utterly wrong. Because of his complexity, Macbeth appears sympathetic to the readers at times. He tells us all about his fears and doubts and seems to be struggling with issues not so different from ours.
The play implies that one must be moderate and aware of the moral principles if one is to live a meaningful life. Despite gaining all the power he desired, Macbeth realizes that his life is futile, and without a doubt, he is the one responsible for ruining his own life and the lives of many others.