Mr. Gore, the chemistry teacher, was my favorite teacher in high school. Maybe it was because of his fiendish laugh, or perhaps his habit of booby-trapping the classroom floor with a substance that would create little explosions whenever a late student walked into the room. You know—things a teacher could never get away with in a post-9/11 world. But I also liked how he expressed things that I would remember for years to come. Even today, I still remember these words: “Nothing comes out of the crucible the same as it went in.”

Mr. Gore described how the crucible reveals everything. Some substances are broken down by the fire of the crucible. Others are refined. Some molecules bond there, while others are separated. Impurities rise to the surface, where they can be skimmed off the top or left to reintegrate back into the substance when the crucible cools. The crucible is a place where substances are refined and defined and changed.

As I’ve taught about the defining moments of King David’s life—the crucible moments that revealed or shaped who he was—I’ve found that the term crucible is familiar to some people but not to others. It’s one of those words we don’t use every day. So before we go on, I should probably be clear on what we’re talking about. Here are the dictionary definitions for a crucible, straight out of Merriam-Webster’s online:

1. a vessel of a very refractory material (as porcelain) used for melting and calcining a substance that requires a high degree of heat

2. a severe test 3. a place or situation in which concentrated forces interact to cause or influence change or development

The first definition, the one Mr. Gore introduced me to in chemistry class, is the picture from which the other two definitions grew. The crucible, usually porcelain, is used for melting a substance in order to separate its elements or change them through intense heat. It can be used to burn off the dross in precious metals in order to purify them. Everything in the crucible is affected, and only the elements that can stand the heat remain.

I have just completed a series of lessons based on Phil Tuttle’s book, Crucible. They are available on Amazon in both print and Kindle versions, as well as part of my Good Questions Have Groups Talking Subscription service. For a medium-sized church, lesson subscriptions are only $10 per teacher per year. Lessons correspond with three of Lifeway’s outlines as well as the International Standard Series. In addition, you get access to lessons like Crucible.