In 1901, Karl Landsteiner identified the ABO blood group system. The discovery explained why some transfusions succeeded while others caused fatal reactions. Safe transfusion later became essential to surgery, trauma care, childbirth, cancer treatment and the management of bleeding complications from anticoagulants.

The discovery of ABO blood groups in 1901 transformed the symbolic representation of blood in literature, allowing poets to explore themes of kinship, identity, and sacrifice with newfound biological specificity. This scientific advancement inspired a deeper examination of human relationships and the essence of life in poetic expression.