Whilst in the life of the intellect, 'contemplation', refers to thinking profoundly about something, in the religious life contemplation is a kind of inner vision or seeing, transcendent of the intellect, facilitated by means of practices such as prayer or meditation.
The word contemplation is derived from the Latin word contemplatio. Its root is also that of the Latin word templum, a piece of ground consecrated for the taking of auspices, or a building for worship, derived either from Proto-Indo-European base *tem- "to cut", and so a "place reserved or cut out", or from the Proto-Indo-European base *temp- "to stretch", and thus referring to a cleared space in front of an altar. The Latin word contemplatio was used to translate the Greek word θεωρία (theōría).
Contemplation was an important part of the philosophy of Plato; Plato thought that through contemplation, the soul may ascend to knowledge of the Form of the Good or other divine Forms. Plotinus as a (neo)Platonic philosopher also expressed contemplation as the most critical of components for one to reach henosis. To Plotinus the highest contemplation was to experience the vision of God, the Monad or the One. Plotinus describes this experience in his works the Enneads. According to his student Porphyry, Plotinus stated that he had this experience of God four times. Plotinus wrote about his experience in Enneads 6.9.
In Islamic tradition, it is said that Muhammad would go into the desert, climb a mountain known as Mount Hira, and seclude himself from the world. While on the mountain, he would contemplate life and its meaning.
In Eastern Christianity, contemplation (theoria) literally means to see God or to have the Vision of God.[note 1] The state of beholding God, or union with God, is known as theoria. The process of Theosis which leads to that state of union with God known as theoria is practiced in the ascetic tradition of Hesychasm. Hesychasm is to reconcile the heart and the mind into one thing (see nous).[note 2]
Contemplation in Eastern Orthodoxy is expressed in degrees as those covered in St John Climacus' Ladder of Divine Ascent. The process of changing from the old man of sin into the newborn child of God and into our true nature as good and divine is called Theosis.
This is to say that once someone is in the presence of God, deified with him, then they can begin to properly understand, and there "contemplate" God. This form of contemplation is to have and pass through an actual experience rather than a rational or reasoned understanding of theory (see Gnosis). Whereas with rational thought one uses logic to understand, one does the opposite with God (see also Apophatic theology).
The anonymously authored 14th century English contemplative work The Cloud of Unknowing makes clear that its form of practice is not an act of the intellect, but a kind of transcendent ‘seeing,’ beyond the usual activities of the mind - “The first time you practice contemplation, you'll experience a darkness, like a cloud of unknowing. You won’t know what this is... this darkness and this cloud will always be between you and your God... they will always keep you from seeing him clearly by the light of understanding in your intellect and will block you from feeling Him fully in the sweetness of love in your emotions. So be sure to make your home in this darkness... We can’t think our way to God... that’s why I’m willing to abandon everything I know, to love the one thing I cannot think. He can be loved, but not thought.”
Within Western Christianity contemplation is often related to mysticism as expressed in the works of mystical theologians such as Teresa of Avila and John of the Cross as well as the writings of Margery Kempe, Augustine Baker and Thomas Merton.
In Christianity, contemplation refers to a content-free mind directed towards the awareness of God as a living reality. This corresponds, in some ways, to what in Eastern religion is called samadhi. Meditation, on the other hand, for many centuries in the Western Church, referred to more cognitively active exercises, such as visualizations of Biblical scenes as in the Ignatian exercises or lectio divina in which the practitioner "listens to the text of the Bible with the 'ear of the heart', as if he or she is in conversation with God, and God is suggesting the topics for discussion." 
In Catholic Christianity, contemplation is given importance. The Catholic Church's "model theologian", St. Thomas Aquinas wrote: "It is requisite for the good of the human community that there should be persons who devote themselves to the life of contemplation." One of his disciples, Josef Pieper commented: "For it is contemplation which preserves in the midst of human society the truth which is at one and the same time useless and the yardstick of every possible use; so it is also contemplation which keeps the true end in sight, gives meaning to every practical act of life."
According to Aquinas, the highest form of life is the contemplative which communicates the fruits of contemplation to others, since it is based on the abundance of contemplation (contemplari et contemplata aliis tradere) (ST, III, Q. 40, A. 1, Ad 2).