Did You Know?
Aristotle was a student of Plato, who was a student of Socrates. Also, one of the students of Aristotle was Alexander the Great.
Excess of anything is bad. It is one of the prime reasons, among many more, which leads to extremism. Aristotle, in the second chapter of Nicomachean Ethics, describes moderation as a virtue. There is a similar concept present in Buddhism, which is known as the 'Concept of the Middle Way', while its counterpart in Chinese philosophy is 'Doctrine of the Mean' by Confucius.
Illustration of confucius
Temple of delphi
Temple of Delphi
In front of the temple of Delphi, a Doric saying is carved, which says 'Nothing in Excess'. The Golden Mean philosophy is also promoted by Christianity and Islam.
Now, arriving at mean is a well-thought out process, after being completely familiar with the circumstances. However, it does not lack emotions. Emotions are a virtue and an important part of life when experienced properly. A person is able to act virtuously, as he is attracted to its 'beauty'.
Aristotle's Golden Mean Theory
Aristotle statue
The middle of two extremes, one of which is abundance and the other one is scarce, is known as the Golden Mean of the two extremes. This, however, does not mean that moderation has to lie exactly at the center of the two, it can lie anywhere in between these extremities. This virtue is similar to technical skills, and everyone must know how not to go overboard or lag behind, but maintain the right amount of balance.
Golden Mean in Greek Philosophy
John keats
John Keats
"Beauty is truth, truth beauty,―that is all
Ye know on earth, and all ye need to know."

-'Ode on a Grecian Urn' by John Keats
The Greeks considered moderation to be an attribute of beauty, and hence, to be true. Thus, it became an object of love that was to be imitated and reproduced. According to a Greek mythological tale, Daedalus, a famous artist, had built feathered wings for his son, Icarus, and advised him not to fly too high. Icarus did not listen to his father, and flew towards the Sun, that caused his wings to melt and for Icarus to fall into the sea and drown. This story is a representation of Aristotle's theory, where Dedalus had asked his son not to go too close to the Sun, an advise that he ignored, leading to his death. This highlights the side-effects of extremism.
Aristotle's Ethical Doctrine of the Mean
According to Aristotle's ethical rule about the Golden Mean, to use a thing with virtue is a kind of moderation, as it leads the particular thing being in a good condition, and allows for its functions to be performed in a proper manner. Aristotle developed this doctrine during the discussion of excellence in the aforementioned book. When the ethical values are projected well, they are able to strike a balance, which makes them advantageous. Maintaining this balance, though, is a difficult task, and humans do not accept difficult tasks easily, which serves as a reason for the lack of virtue.
Examples of Golden Mean Philosophy
Courage is a good example of this philosophy. Excess of it is considered as rash or overconfident, while its deficiency is known as cowardice. Another example on the similar lines is that of generosity, which is a mean. Excess of it will be wastefulness, whereas, deficiency will be stinginess. As mentioned earlier, the Golden Mean need not lie exactly at the center of the spectrum ranging from excessive to deficiency, it can be anywhere in between. Consider, for example, if a person was cheated out of his life savings, then, the person would be angry, and it would be very close towards being excessive, an extreme. As opposed to, say, a minor accidental mishap, which might not get the tempers rising, and the lack of anger would inch towards indifference, another extreme. In both cases, however, both the reactions are considered 'mean', due to the varying level of involvements.
Aristotle's predecessors were of the same opinion when it came to moderation. Socrates taught that a person must choose mean and avoid excess as far as possible. While according to Plato, if something was disproportionate, it was evil, and hence, to be despised.