What is the theme of the traditional ballad "Sir Patrick Spens"?

There are a number of themes which are explored in the poem.  Prominent among these are the themes of loyalty, suffering and loss, and courage.

Loyalty is a central theme as it relates to both Sir Patrick and his crew.  When Sir Patrick is ordered by the king to go to sea, he is aware that it is a dangerous time of year for sailing, yet he promptly obeys.  His men also acquiesce without protest, because they are loyal to Sir Patrick.

The theme of suffering and loss common to the human condition is also explored in the poem.  The impact of the tale comes from the tragic loss of an exceptional man in Sir Patrick Spens, and the finality of the destruction of the ship and everyone aboard.  There is a sense of universality in Sir Patrick's lament when he says, "O wha is this has done this deed, this ill deed done to me".

The theme of courage is developed through the noble character of Sir Patrick.  He is a better man than the lords, who do not want to get "their fancy cork-heeled shoes" wet even aboard ship, and has more substance than the ladies, who are pictured as idly rich, insensitive, and demanding.  The steadfast bravery with which Sir Patrick submits to the king's command and performs his duty even to the face of death might be representative of the courage human individuals must demonstrate in facing whatever trials come their way.