"Since the Lord is no longer visible among us, everything of him that was visible has passed into the sacraments." -- Saint Leo the Great

Christ instituted the Sacraments/Mysteries of the new law. There are seven: Baptism, Confirmation, the Eucharist, Reconcilation, the Anointing of the Sick, Holy Orders and Matrimony. The seven Sacraments/Mysteries touch all the stages and all the important moments of Christian life: they give birth and increase, healing and mission to the Christian's life of faith. There is thus a certain resemblance between the stages of natural life and the stages of the spiritual life. (CCC 1210)

Why Sacraments/Mysteries?

The Catechism of the Catholic Church teaches:

“Sacraments are ‘powers that come forth’ from the Body of Christ, which is ever-living and life-giving. They are actions of the Holy Spirit at work in His Body, the Church. They are ‘the masterworks of God’ in the new and everlasting covenant” (n. 1116).

• The Sacraments/Mysteries of Initiation are Baptism, Confirmation, and Eucharist. These are the three sacraments that make a person a Christian—the sacraments that initiate someone into the Body of Christ.
• The Sacraments/Mysteries of Healing are Reconciliation and the Anointing of the Sick. These two repair what is broken in the body and soul.
• The Sacraments/Mysteries of Vocation are Marriage and Holy Orders. These sacraments build up the Church, in number and in strength; they are directed toward the good of others rather than oneself.