To illustrate this double grace, Calvin uses a picture from nature—the light and heat of the sun: Christ, our righteousness, is the sun. Justification, its light; sanctification, its heat. The sun is at once the sole source of both such that its light and heat are inseparable. At the same time, only light illuminates and only heat warms, not the reverse. Both are always present, without the one becoming the other. 24