Who is Sebastiana Maria de Jesus from Baltasar and Blimunda and what is their importance?

Sebastiana Maria de Jesus is Blimunda's mother. She is a visionary and a heretic.
Sebastiana is burned at an auto-da-fe by the Holy Inquisition for being a prophetess, who preaches a mystical unity with God. Her last words to her daughter were to ask the man next to her his name. The man turns out to Baltasar, and thus, she sets into motion the love affair and all of the events of the book that follow.