Why do Catholics celebrate 7 days and 30 days after a person’s death?

QUESTION: why did the Catholic Church have a tradition of celebrating 7 days and 30 days after death, in contrast to Orthodoxy, where it is customary to celebrate 9 and 40 days?

ANSWER: the sacrament of Baptism, that is, the birth “of water and of the Holy Spirit,” introduces a person to eternal life, the sprout of which was the resurrection of Jesus Christ. The life-giving stream that passes through the life of the baptized does not dry up with the completion of their earthly journey, because, as the liturgy says about the departed, “Your faithful, Lord, life is transformed, but not taken away, and when her earthly dwelling is destroyed, it acquires an eternal abode in heaven. ” From the very beginning of its existence, recognizing the communion of the whole mystical body of Christ, “the Church of the pilgrims honored the memory of the dead with great reverence, and since the thought of praying for the dead that they would be released from sin is holy and pious (cf. 2 Mack 12:45), it exalts for them prayers for the dead. “