Often, great cruelty or injustice has been inflicted upon ourselves, by our own hands and upon our own heads.

This couplet beautifully points out a universal truth: often, the difficulties we face are a result of our own actions. It's a gentle reminder that sometimes, without realizing it, our choices, decisions, or even our words can lead to unintended consequences or 'heavy injustices' upon ourselves. It encourages self-reflection, urging us to look inward and understand how our own behavior might be contributing to our challenges. It's about taking personal responsibility and learning from our experiences, recognizing that while external factors exist, our internal landscape and agency play a significant role in shaping our destiny.