The song "Tus Cartas Son Un Vino" by Joan Manuel Serrat tells the story of a person who deeply misses their loved one. The lyrics describe how the letters received from their loved one are like a intoxicating wine that affects them profoundly. These letters are the only nourishment for their heart, providing the emotional sustenance they need while being apart. The singer admits that in their absence, all they can do is dream, just like the sea that longs for their loved one's body, which is bitter like the sea itself. Despite the singer being physically absent, they ask their loved one to continue writing to them, promising to reciprocate the act of correspondence. The lyrics metaphorically express the singer's longing for their loved one's words and emotions, comparing it to the nourishment they receive from the letters. Even if the singer's body is underneath the earth, they find solace in the letters, giving their heart to them as if it were a pasture or grass. The words of the letters essentially become their sustenance. The song conveys a deep sense of longing, desire, and a connection maintained through written correspondence. It paints a picture of the singer's intense emotions and their reliance on these letters as a means of staying connected to their beloved, even in their physical absence.