Step 1: The question asks for the central theme of the poem "The Empty Heart" by Periasamy Thooran.
Step 2: The poem is a parable about a man who prays for wealth and is granted a magical pitcher that can never be filled.
Step 3: The man's relentless desire to fill the pitcher, sacrificing his health, family, and happiness, is a clear depiction of insatiable 'Greed'. However, the consequences of this greed—his frustration, his rage at his inability to succeed, and his ultimate demise—stem from an underlying, destructive 'Anger' with his situation and himself. While greed is the cause, the poem highlights the destructive anger that it generates.