Serenity

Serenity was a feeling of calm, peacefulness, and tranquility.

Spock said to his young self, "There is some human blood in my family line. It is not fatal. What you do not yet understand, Spock, is that Vulcans do not lack emotion. It is only that ours is controlled. Logic offers a serenity Humans seldom experience in full. We have emotions but we deal with them and do not let them control us." (TAS: "Yesteryear")