"The one who is slow to anger is better than the mighty, and the one who rules the spirit (is better) than the conqueror of a city," Prov. 16:32.
"The one who restrains words has knowledge, and the one who has a cool spirit is a person of understand," Prov. 17:27.
The book of Proverbs gives what might be called "counterintuitve wisdom." We think certain things are true in life but then we read Proverbs, and we are often told the opposite. These two Proverbs present counterintuitive wisdom with respect to the emotions. Their major point is that the more powerful person in life is one who is both slow and cool, rather than fast and hot. Our culture, increasingly, favors people who are quick-acting and decisive, eager to pursue hot deals rapidly.
But let's listen to these words from Proverbs. The thoughts are both expressed in a form of poetry called "parallelism" - the second line of the Proverb gives a parallel thought to the first, though varying the words. Thus, "slow to anger" = "ruling the spirit" and "restraining words" = "cool in spirit." The one in Scripture who is first said to be "slow in anger" is God Himself, in Exodus 34:6. Thus what Proverbs is really teaching in these words is behavior imitating God.
What is that behavior? To realize, first of all, that slow is better than fast, and that an ability to calm the roiling waters of the of the emotions is better than putting down a rebellion in a far-off city. We are confronted with situations nearly every day where the "temperature" of our spirit may rise. Imitating the Divine patience towards us with some patience of our own is paramount. Then, second, we realize that a cool, rather than hot, spirit is better. We attain that through restraint of words. We spend most of our life thinking about what we should have said; we rarely say to ourselves, "I should have kept my mouth shut." But the key to Biblical coolness is restraint, in words and emotions. That is the heart of Proverbs.