Layers of Dhyan(Concentration)

First layer of Dhyan is named Baikhri(Speech or to speak)
Second layer is called Madhyama(Thoughts or to think)
Third layer is Pashyanti(To see or to view)

First layer is to talk
Second layer is to think and
Third layer is to see
Fourth layer is called "Para". In fourth layer there is no talking, no thinking and no seeing.
In all the four layers abides our Atma (Soul)

We mostly live in the first layer like singing bhajan, devotional songs, prayer, kirtan, music etc.
Sometimes we reach upto the second layer of thinking(Vichar). We can hardly reach upto the layer of Seeing(Dekhna) and it is very, very difficult to reach at the fourth layer.