Generally when we think of the word "sober," we simply think not drunk. It turns out that is an important definition of sober, but the word has a much deeper meaning as it is used in the scriptures. According to the Oxford English Dictionary, soberness is characterized by the absence of excess or indulgence.
A sober person is grave, serious, solemn, having or implying a serious mind or purpose. A sober person is also quiet or sedate in demeanor, dignified or discreet in deportment and of a serious character. A sober person shows no trace of haste or impatience and is free from harshness and violence and is of a moderate disposition, not readily excited or carried away. A sober person is one who has calm and dispassionate judgment and is not desirous of great things or high estate but is free from extravagance or excess. Such a person is guided by sound reason and is sane and rational. Interestingly, sober is also connected to fasting.