This book is based on 2 different texts.(but, they are handling the same love story about Abelard and Heloise)
 
Primary Text (letters): The Love Letters of Abelard and Heloise, Pierre Abelard
Secondary Text (poem): Eloisa to Abelard, Alexander Pope
 
By juxtaposing letters with a poem, it creats tension, and emphasize the sadness of their tragic love stroy.
It includes two direction of justified texts based on a sender of message.