This research aims to test the hypothesis planteda: “The Holy Spirit, the Spousal origin” in the super Cantica Expositio Canticorum of William of St. Thierry. From this place of communion flows the Spousal where human beings are called to share in the Trinitarian life through the Holy Spirit, through the hypostatic union of human and divine in Christ. This is a complex and novel nature, developed from a dogmatic content that the author has deployed as mystical theology Trinity.Key words: Song of Songs, William of Saint Thierry, Holy Spirit, Trinity, Christ.