Its a term in psychology taken from Greek myth. Cassandra was the daughter of King Priam and Queen Hecuba, she was a prophetic seer but lacked the power of persuasion and was never believed. So when we say someone has a "cassandra complex" its saying they know something terrible is going to happen but they can't or won't do anything to prevent it.
by synthetik_smurf August 15, 2005