Meditation is the highest method of religious practice in various directions of religion.
It is meditation as a method that allows one to cognize Living God and — at the very end — to come to Mergence with Him.
Meditation is work of the consciousness. The mind occupied with worldly concerns has to be silent in meditation, and there are special techniques that help one to learn to stop the work of the mind for the time needed for meditation. This is called mastering the mental pause. 
A consciousness (in fundamental psychology) is energy aware of itself. This is a human being itself, in the embodied or unembodied state. A synonym of the word consciousness is the word soul.
To any reasonable person it must be clear that such expressions as “my (his, her) soul”, say nothing of “to lose soul” or “save our souls” are wrong and caused by misunderstanding. I repeat: soul is a human being itself.
As for the mind, it is a function of the consciousness; thus a person who parted with the body due to its death still possesses the mind and the memory.
But the mind of an incarnate person works in connection with the brain.
A consciousness can be developed from tiny sizes up to the cosmic sizes. The process of such development of the consciousness is called crystallization. It is meditation and crystallization that Jesus talked about when He said “God is Spirit, and they who worship Him must worship in spirit and in truth” (John 4:24). That is, one must perceive oneself not as the body but as a spiritual substance — consciousness — and one, as a developed consciousness, has to aspire to the Consciousness of the Creator, Who is Spirit, the Most Perfect Consciousness.
Man can go through the initial stages of the development in raja yoga.
The further advancement is realized on the stage that Krishna called buddhi yoga — the yoga of actively developing consciousness.
In the classic scheme of advancement through the stages of spiritual self-perfection developed by Patanjali , meditation (dhyana) is on the seventh place. It is preceded by learning ethical principles, rules of hygiene, bringing the body into a healthy state with the help of special complexes of physical exercises (hatha yoga), cleansing and developing the chakras and bioenergy channels, learning to control the mind, and many other things. In the Patanjali’s scheme, meditation leads to Samadhi, where large work with the help of the methods of buddhi yoga takes place.
Sathya Sai Baba says the following about the highest stage of mastering meditation: “The correct meditation is mergence of all thoughts and senses with God,… when all actions originate from God’s Consciousness and not from the mind of man” [20,60].
There are three aspects of Perfection: Love, Wisdom, and Power.
The three corresponding directions of spiritual work, which help one to master these aspects, are ethical, intellectual, and psycho-energetical directions. The priority should be given to the two first directions. Meditation is the main method of the third direction. It is in this way that all true spiritual schools work.