This fundamental study, published in 1920, is considered one of Freud's most challenging yet also one of his most important works. The drive theory introduced here, contrasting Eros and the death drive, continues to spark discussions to this day. With this writing, Freud was far ahead of his time in elucidating the significance of symbolic processes for the development of the subject and their unconscious desires, thereby establishing a scientific milestone that remains relevant today. A detailed line-by-line commentary, along with an insightful afterword, provides valuable aids for understanding.