Muharram marks the start of the Islamic calendar, however it also marks the start of the great tragedy of Karbala in which the family of the prophet were killed in a battle against the tyrant Yazid. For this reason, many Muslims do not start the new year with celebration but with mourning and commemorating this tragedy.
The soul is in need of tragedy. Mourning is a process of purification and catharsis. Through mourning the tragedy of sacred personalities, your personal suffering and tragedy melts into theirs and their tragedy is ultimately not a tragedy, because they willingly sacrifice their life for the sake of The Truth and The Good.
The tragedy may have happened thousands of years ago, but sacred history is a living reality. In reflecting over the tragedy you can find yourself, because every type of person is represented.
When seen as a battle between light and darkness you will find yourself somewhere between the personification of darkness and light represented by the tyrant Yazid and Imam Hussain(as).