This quote by Publilius Syrus is a suggestion that we need to not be too lenient when it comes to punishing those who do wrong. By sparing the bad, we are essentially enabling them to continue their bad behavior, which can have a negative influence on the excellent. This quote is a caution that if we do not do something about it versus those who do incorrect, we are in fact doing an injustice to those who are doing the ideal thing. It is necessary to keep in mind that justice should be served and that those who do incorrect ought to be held liable for their actions.
The quote likewise acts as a pointer that we need to not be too fast to judge those who have done incorrect. We should take the time to understand the scenarios and the motivations behind their actions prior to we pass judgement. We should also bear in mind that everybody can making mistakes which we should be willing to forgive and provide individuals a 2nd chance.
Eventually, this quote is a reminder that we must not be too lenient when it concerns punishing those who do wrong. We should aim to be fair and just in our dealings with others, and we must keep in mind that by sparing the bad, we are really doing an injustice to those who are doing the right thing.