“It is better to discuss things, to argue and engage in polemics than make perfidious plans of mutual destruction.”

Simplified Meaning:

Talking and arguing with others is much better than making secret, harmful plans to hurt each other. Imagine two friends having a disagreement. If they sit down and talk about what's bothering them, they have a chance to understand each other's perspectives and fix their friendship. However, if they stay silent and start secretly doing things to harm each other, like spreading nasty rumors, their friendship will likely end badly. In history, open discussions have prevented wars, while hidden plans have led to big conflicts. If we want peace and understanding in our relationships, we should always choose to discuss and work out problems rather than plotting in secret to cause harm. For example, in a workplace, a team that openly discusses their issues can find solutions together, rather than hiding resentments which could destroy team spirit.