This study offers a systematic and comparative account of three major medieval commentaries on the rite of the Holy Mass: St. Thomas Aquinas’s exposition in the “Summa theologiæ,” Pope Innocent III’s “De sacro altaris mysterio,” and “De mysterio missæ” attributed to St. Albert the Great. At its centre stands the Roman Canon—the core of the Latin Mass tradition—whose enduring liturgical use prompted centuries of theological reflection. Bridging perspectives of doctrine, sacraments, and liturgical exegesis, the dissertation addresses the long-standing tension between the spiritual and philological schools of interpretation. By retrieving the Thomistic doctrine of spiritual signification—grounded in sacred doctrine and operative in Scripture, sacraments, and liturgy—it proposes a theological resolution. This Thomistic ressourcement demonstrates that the spiritual sense is not a subjective imposition, but an objective content of the rites themselves—signifying the passion of Christ, the sanctification of the Church, and the final consummation of the mystical body. In doing so, it contributes to the renewal of liturgical theology and highlights Aquinas’s synthesis as a vital key for understanding the Holy Mass in the Western tradition.