To a person considering the Catholic faith, it may seem anachronistic or even useless that the Church still supports and encourages women and men to live a “cloistered” life, a life removed from ordinary society and perhaps spent in silence. Sure, maybe in the 12th century this sort of thing made sense, but today in America? What possible use is such a monastic existence? It seems so Dark Ages and maybe even a reason to avoid a church that still embodies such things. 
Like everything else Catholic, cloistered life fits into a big system of thought
Catholics view the church differently than do most other Christian fellowships. We understand the church in an organic, holistic sense. We understand the church to span the ages and even to span varying realities.
What I mean by “organic” is that Catholics understand a phrase St. Paul often uses to be an accurate description of the entire church, not just the local congregation. St. Paul says the church is “the body of Christ” and he uses this way of speaking to illustrate various functions within the church. As far as I know, all Protestants consider this to be a description of how a local congregation carries out practical ministry. The idea is that some people preach and teach, others help poor people, another group takes care of finances – and thus at a congregational level the functions of the body of Christ are accomplished with different folks doing different work.
Catholics do, of course, see the legitimacy of this Protestant understanding of the idea of the body of Christ. It is exactly what goes on at a parish. But we also understand the body of Christ is more extensive than the local congregation and has a significance apart from simply summing up the local congregations. The Catholic Church has an existence and work whose context is the whole Church. Tasks of magisterium and formation and universal call are given the Church as a whole, not to any parish or even to all-the-parishes-summed-up-as-a-whole. The earth is leavened not only by the local congregations, but also by the entire Catholic Church as the body. Not even time or death limits the Church in its role as the body of Christ. Saints in heaven continue to pray for the church on earth at a given time in an ever-increasing intensity of intercession.
Here’s what that has to do with cloistered religious life
Cloistered life is part of this “whole Church” role.
Nuns and brothers (called “religious”, with the word used as a noun) who live a cloistered life spend the larger part of their time praying and contemplating God. In some cases they engage in perpetual adoration of the Blessed Sacrament (in other words, they pray with a consecrated Host displayed in a monstrance). Silence may be the daily rule. Many of these nuns and brothers do not go out into secular society. They almost surely wear a habit. Each day and all of life is given over to God in prayer and contemplation and in whatever work the group uses to support itself.
Religious undertake what are called the Evangelical Counsels. They promise chastity, poverty, and obedience to their superior. In a progression of promises to God, the religious enters into full dedication to God. Religious orders promulgate rules to regulate daily life for the members of the order.
This is how the website CloisteredLife.com describes things:
Cloistered life is a formal way of life recognized by the Church to invite men and women to find within the hidden life of the monastery a place where they can experience the loving exchange of hearts with Christ Jesus. In this enclosure, they find their true selves and experience a foretaste of Heaven!
These people not only pray the prayer of the Church, in a sense they are the prayer of the Church! Think of it – at any given moment, tens of thousands of Catholic religious are praying for the Church, for her work, for those lost in the world. They praise God and adore Jesus in the Sacrament. The world-wide body of Christ has this group of people separated from ordinary life and dedicated to helping you and me and every other soul alive do the will of God.
This is from the 1999 document Verbi sponsa
‘The pilgrim Church is by very nature missionary.’ Cloistered nuns fulfill that mission by dwelling at the missionary heart of the Church, by means of constant prayer, the oblation of self and the offering of the sacrifice of praise. Their life thus becomes a mysterious source of apostolic fruitfulness and blessing for the Christian community and for the whole world.
Where I pray
Several times a week, I go to a monastery of cloistered Poor Clare nuns to pray. The monastery provides a chapel where the public can pray. About ten feet up the front wall of the chapel is the Blessed Sacrament in a monstrance. On the other side of the wall there are always nuns praying. To hear them singing and reciting – to know they pray for me, even though they don’t know my name – to know that their lives are wholly given to God in this particular way. To know their order has existed in just this way for centuries. To know their prayer fulfills the promise of James 5, “the fervent prayer of a righteous person is very powerful”. These things sometimes fill my heart almost over-full as I join my prayer and heart to the nuns I cannot see. It is a sweet, pure, odd affection that somehow makes me want even more to bury myself in the will of God. I do not doubt I am carried by their prayers.
This is not something from the Dark Ages. This is the eternal Church of Christ praying from her heart for the whole world and for you and me. I thank God for a church that calls men and women to a life of cloistered prayer.
The prayer of cloistered religious is at the heart of the Church.
The Catholic Church holds holy a life dedicated to prayer and the Evangelical Counsels.
We should never believe the work of the Church is done only in public ways.
What a grace to have a Poor Clare Monastery in your area. Please pray for our Catholic Daily family, that this Lent may be a time of great rebirth in the Spirit.
Yes, it’s a wonderful thing. The monastery is huge and for the most part empty now, since the number of vocations are down. There are three extern nuns who are just sweet, wonderful people.