As per Yoga and Vedanta, meditation is a mental process by which the meditator becomes one with the object of meditation and there are three stages of meditation.
There are three stages in this mental process:
Stage 1: Concentration or dharana
- This is the first stage of meditation.
- In this phase one has to have one-pointed focus on any fixed object, whether internal or external
- One unit of concentration is equal to 12 seconds of continuous uninterrupted focus on such object
- Concentration is the way to learn about a subject
Stage 2: Meditation or dhyana
- When concentration becomes effortless and continuous, it is known as meditation
- Twelve units of concentration is known as Meditation
- In other words, dhyana involves at least 2 and a half minutes of one pointed uninterrupted focus
Stage 3: Total Absorption or samadhi
- This is the culmination of the meditation process
- Twelve units of Meditation is known as Samadhi
- In other words, samadhi involves at least 30 minutes of one pointed uninterrupted focus
- Smadhi is the phase when the Meditator unites with the object on which it wants to seek knowledge
Source: Meditation & Its Practices, Swami Adiswarananda, Advaita Ashrama
