I recall once reading something to the effect: "Gossip is not only damaging to its target, but also to the gossiper and the one hearing the gossip."
Here is a great colloquism: "It takes one to know one."
And a story:
There was once a king who gathered together a council of his vassals, and asked them to compile a library of all the wisdom in the land. After 40 years, they had filled the room with books, wall to wall with volumes of wisdom.
At seeing this, the king knew he could never have time to read all these books, so he asked that the vassals compile all the most useful wisdom into a single volume. After another 20 years, they had done just that.
Upon reading this single text, the now elderly king was enlightened. Alas, he knew that this bliss would evaporate as soon as he engaged again in his worldy duties. He also had hoped to convey this enlightenment to all the people of his land, though many of them were illiterate.
So the king again convened his vassals, and asked that they construct a single sentence that would bring one to peace. He asked that these words serve well both in times good and in times bad.
The king was surprised the next day, when his vassals had returned with the essential phrase:
"This too, will pass."