Runes of information

Lucius had begun to study fire. A simple fire that he created quite easily with a simple technique. Yet the mystery that Lucius was trying to solve was far more complicated than anything he had tried to solve before. He knew what fire was, yes. He knew various fire runes and the primordial fire rune, yes. But he didn't know how a fire rune became fire. It seemed like a simple question and was similar to his question of how runes worked themselves which he had concluded he did not know and even could not know yet but this was a more pinpointed question he was pondering. What made a primordial rune work? What made it different from some simple lines.