We don't all become Emily Dickinson

Loneliness is not the same as being alone. Many people have times when they are alone through circumstances or choice. Being alone can be experienced as positive, pleasurable, and emotionally refreshing if it is under the individual's control. Solitude is the state of being alone and secluded from other people, and often implies having made a conscious choice to be alone. Loneliness is unwanted solitude. Loneliness does not require being alone and is experienced even in crowded places. It can be described as the absence of identification, understanding or compassion. Loneliness can be described as a feeling of isolation from other individuals, regardless of whether one is physically isolated from others or not. It may also be described as a yearning for love or companionship, which is unfulfilled, but cannot seemingly be achieved, or may stem from the lack of love in one's life, and hence may lead to emotions such as rejection, despair and low self-esteem. Feelings of loneliness may be similar to feelings of the death or loss of a loved one.
In their growth as individuals, humans start a separation process at birth, which continues with growing independence towards adulthood. As such, feeling alone can be a healthy emotion and, indeed, choosing to be alone for a period of solitude can be enriching[citation needed]. To experience loneliness, however, can be to feel overwhelmed by an unbearable feeling of separateness at a profound level. This can manifest in feelings of abandonment, rejection, depression, insecurity, anxiety, hopelessness, unworthiness, meaninglessness, and resentment. If these feelings are prolonged they may become debilitating and prevent the affected individual from developing healthy relationships and lifestyles. If the individual is convinced he or she is unlovable, this will increase the experience of suffering and the likelihood of avoiding social contact. Low self-esteem will often trigger the social disconnection which can lead to loneliness.
In some people, temporary or prolonged loneliness can lead to notable artistic and creative expression, for example, as was the case with poet Emily Dickinson, and numerous musicians. This is not to imply that loneliness itself ensures this creativity; rather, it may have an influence on the subject matter of the artist.

Source: Wikipedia (so who knows, really)

also see: http://en.wikipedia.org/wiki/Pit_of_despair