The Thorn Birds (1983) who sent the fire?

Meggie Cleary: That dear and gentle God who has taken from me everyone that I've loved most in the world. One by one. Frank, and Hal... and Stuie... and my father. And you, of course. Always you. If God is merciful... left me no one else to grieve.
Ralph de Bricassart: He is merciful, I know you can't see that now, but he is. He spared the rose. He sent the rain.
Meggie Cleary: Oh Ralph... who sent the fire?