Fools with no sense
Go about as their own enemies,
Doing evil deeds that
Bear bitter fruit. (translated by Gil Fronsdal)
This verse is an expression of the principle of karma, the law of causation: good actions produce good results and bad actions produce bad results, and not only for the person performing the action.
Individual karma is not deterministic, it is not the whole story of why anything happens in our lives, but it is the only part that we have control over. Things we did in the past, for good or ill, are beyond our reach, and many impersonal events affect us in myriad ways, but we can direct our actions in the present. Understanding this basic principle, that we are responsible for what we do and say in the world and for how those actions help or hinder us and others, is essential to any growth.
An earlier verse in the Dhammapada re-states the principle:
Whatever an enemy may do to an enemy,
Or haters, one to another,
Far worse is the harm
From one’s own wrongly directed mind. (verse 42)
This is a distinguishing feature of most forms of Buddhism among other world religions. We do not look to an external power, earthly or heavenly, to regulate our actions and punish or reward us; we rely on the laws of nature to perform this function. If we are unkind or unfair to others, the result is that we hurt other people, damage our own hearts, and acquire a reputation as mean and unreliable. If we are generous, honest, and fair to others as a matter of course, we enjoy the inner warmth of knowing that we are a reliable source of joy, strength, and comfort, to ourselves and to others.
Events and energies come at us non-stop throughout or lives. Our domain of control is how we respond to what is both in front of us and inside of us.