Brain Snacks: Tasty Tidbits of Knowledge
Allende began writing this novel in the form of a letter to her dying grandfather on January 8, 1981. It became such a success that she considers January 8th to be a lucky day, and now begins all of her novels on that date. (Source)
Allende's novels Daughter of Fortune and Portrait in Sepia chronicle the lives of the ancestors of the del Valle family, and could be considered prequels to The House of the Spirits.