By oneself is evil done.
Born of oneself, produced by oneself,
It grinds down those devoid of wisdom,
As a diamond grinds down a gem. (translated by Gil Fronsdal)
The past is gone and the future is unreachable. The only time we have available to influence any karmic outcomes is now; the only power we’ve got over our own futures is in the decisions we make now about what we’ll do and say. In the vernacular, we don’t choose what cards we are dealt; we can only choose how we play them.
Why do bad things happen to good people? Why do good things (apparently) happen to bad people? There is very little we can know as to the why of things. Why do some people who smoke all their lives not develop lung cancer? Why do some people who have protected themselves from the sun all their lives develop skin cancer? The karma of these questions can include genetics, random influences, and a myriad of other factors that are invisible to us.
Given that there are no guarantees, what’s our best course? We know from the evidence that wholesome motives and actions will, on average, over time, produce good outcomes. If we are kind and thoughtful and diligent, we’ll develop meaningful friendships and honest working relationships. We also know that when we follow our less wholesome inclinations, we spend time with people who may not have our best interests at heart. We might take the easy path rather than the awkward one, thinking that we are avoiding difficult consequences, when in fact we may be creating unhealthy, or even dangerous, outcomes.
Because the whole complex of karmic causes and results involve different time scales and depths of intention, calculating outcomes is impossible for us. If we are wise, we’ll avoid doing anything that might be called evil because we’ve chosen to live a caring, fully-engaged life. The verse quoted above reminds us that while people may be kind or unkind to us, our actions of body and speech and mind are the primary determinants of whether we build our wisdom or wear it down.