Early modern science and technology further revolutionized the heart-book metaphor. After Gutenberg, the book of the heart was often pictured as a volume. And as physicians reduced the heart to a pump, forcing philosophers to relocate the soul or self to the head, the book of the heart was gradually replaced by "the book of the brain." This more cerebral book of the self survived into the twentieth century, when even Freud adapted it to his theories of the psyche, and Jacques Lacan, one of Freud's psychoanalytic successors, directly likened the unconscious mind to the "censored chapter" of a book. Literary authors also adopted it, as when Virginia Woolf, in (1927), describes a character's psyche in terms of "the infinite series of impressions which time has laid down, leaf upon leaf, fold upon fold softly, incessantly upon his brain."
The book of the heart was still used in a romantic sense, as in Edith Wharton's 1905 novel, (recently made into a movie), which describes its heroine, Lily Bart, as "a keen reader of her own heart." And even more recently it has showed up in song lyrics, as in Paul McCartney's hit tune from the 1973 film whose opening line goes: "When you were young, and your heart was an open book...."
The most complete physical embodiment of the romantic book of the heart is the famous known as the (c.1475). One of several surviving heart-shaped manuscript books containing poems or music, but the only one to contain colored illustrations, this book is now kept at the Bibliothèque Nationale in Paris. As a collection of love poems set to music, this elegant illuminated manuscript in the form of a double heart takes the heart-book metaphor to what seems like its absolute limit. At the same time, it turns the metaphor inside out by making interior and metaphorical writing into literal and external writing once again.
The amorous book of the heart evoked by secular poets assumed an even more vivid and concrete form in the heart-shaped songs and books produced by late-medieval and Renaissance artisans. A heart-shaped song composed by Baude Cordier (c.1400) survives in the famous Chantilly manuscript containing shaped musical scores. Addressed to a lady, the song begins with a series of compliments and goes on to offer her the lover's heart: