St. John Of The Cross: Ascent of Mount Carmel Chapter 2 Analysis In Ascent of Mount Carmel, Chapter 2, St. John of the Cross mentions that in the Book of Tobit, Tobias was instructed by an angel that he must wait three nights before he could have any union with his bride. On the first night, Tobias was asked by the angel to burn the heart of a fish to symbolize that the human heart is attached to worldly things; by burning the heart, we are freeing ourselves from that attachm