In his scholarly review of medieval beliefs about the heart, The Book of the Heart, Eric Jager documents how a society that adopts a new medium of communication reinterprets the metaphor of the heart. A literate society begins to interpret the heart metaphor in ways that reflect the characteristics of their communication technology. In literate Greek, Hebrew and later Roman circles, the heart was described as a tablet upon which “impressions” were recorded, or as a scroll which one could unfold to review thoughts and experiences. When the codex and then the printed book dominated as communication technologies, the heart was described as a book upon which one’s memories were inscribed.
The heart book was private, available only to the individual for review. The painting of The Last Judgment from the Cathedral of St. Cecile in Albi, France, shows the souls of the dead, with their secret heart books displayed on their chests. (Jager, 2000). In the afterlife, the heart book was opened to determine how the deceased would be judged, and what rewards or punishments their life merited. Jager (2000) notes that:
The double sense of the word “character,” both textual and ethical, further emphasizes that each person is responsible for “writing” his own life. (p.140)
What we see here is a vivid depiction of what McLuhan (1962) referred to as “the interiorization in man of the structures of earlier technology.” (p. 174).
That medieval writers and artists would imagine the heart as a book illustrates how a communication medium can determine the interpretation of the metaphor of the heart.
As the textual influence took hold, the heart became the seat of memory, involved with the recording of life and the recollection of experiences. According to Jager (2000),
Memory was often regarded as a specific function of the heart, as embodied in terms such as recordatio, with recollection figured expressly as the “reading” of an inward book. (p.122)
During the later Middle Ages, book metaphors also seem to have grown in popularity as actual books proliferated among the laity and as reading and writing became more widely familiar practices, in turn encouraging new mental habits and reshaping notions of selfhood. (p.104)
Another consequence of the secular spread of books after the invention of the printing press was transformation of the metaphor of the heart into a romantic image. Where Christian theologians would open their “heart books” to the words of God, the later lay reader would transcribe the attributes of his true love onto his heart. As medieval readers interiorized the metaphor of the heart as a book, they also exteriorized it in specially designed heart shaped manuscripts and later, printed books. Images from this era depict earnest young men grasping books that are literally shaped like a heart.
The image of the heart in “Young Man Holding a Book” is not the physical heart, but the Valentine heart we know so well. Perhaps the origin of this design comes from these efforts to externalize the book of the heart. You start with the actual physical heart, from which you want to create a shape that can function as a manuscript. Perhaps you invert it to make it easier to hold. When the heart book is opened, it appears as a valentine. Here we see a possible example of how the dominant medium of communication can influence the metaphor of the heart and the symbolism of romantic love. It is also important to note that the substituting the graphic depiction of the heart with an iconic valentine moves the metaphor of the heart to a different level of abstraction and further encourages metaphoric as opposed to the literal usage.