Theseus returns, no sails

Theseus had promised his father King Aegeus that if he should survive the ordeals of Crete's labyrinth, then he would return with sails of white. King Aegeus awaited on a cliff every day looking out at the sea waiting for the return of his son. When the fateful day came, King Aegeus recognized the ship and noticed the black sails. Believing his son had perished in Crete, King Aegeus threw himself off cliff and died in the sea. Thus, Greece's main sea became the Aegean sea.

But how could Theseus have been so neglectful to cause the death of his father?

Theory #2: Theseus actually wanted his father dead. He had his crew row the ship back without sails...confusing King Aegeus. Then Theseus snuck up the side of the cliff and greeted his father with a knife and a kick off the cliff. Later, he tells a sob story of his neglect to change the sails to win over the heart of the masses...