What is the importance of letter writing in the memoir, Waiting For God?

Letter-writing is the primary means of communication between Simone Weil and Father Perrin. The letters contained in this book (six, addressed to Father Perrin from Weil) may only be representative of one side of their conversation, but they show the depth and richness of their friendship. These two individuals rarely met in person, so the letters--equal parts personal, spiritual, and intellectual--became the medium of their relationship and interaction.