Rabbi Chizkiyah says that the sore is considered a sore when the white that indicates Chesed does not remain as it is but turns red that indicates judgment. It is written that Esau came out red at birth, so judgments dwell in him. If the sore began red and has turned white, it is becoming purified; if it began white and has turned red it begins to be defiled. The priest can recognize all these things. Rabbi Yehuda and Rabbi Yitzchak talk about why Elisha obtained a double portion of Elijah's spirit.