The mind can be steadied by practicing repeated concentration and meditation on a visual form. The particular form can differ according to the individual’s temperament and taste. Some examples are: the steady flame of a candle, a picture of a beloved saint or teacher, the symbol OM, a yantra, etc. Form meditation usually begins with tratak or steady gazing at the physical picture of the form. As you practice this, you may simultaneously repeat your chosen mantra. This steady gazing progresses into clear mental visualization of the object of concentration. An example of form meditation is given below,
A yantra is a mystic symbol in the form of a geometric diagram. Those who went into deep meditation experienced something in the unconscious levels of the mind. Upon returning to normal consciousness, they expressed what they had experienced in the form of mantras, or mystic sounds, and yantras.
This yantra is a diagram of the cosmos. The dot in the center represents the absolute consciousness. The surrounding circles are the subtle expressions of the three forces of nature which begin to manifest as the yantra spreads outward.
To practice meditation with the yantra, begin by having a picture of it in front of you at eye level. Gently gaze at it, holding the main part of the attention on the central dot. Do not strain the eyes. After some time, close the eyes and visualize the form mentally.
When visualization becomes difficult, open the eyes and practice the gentle gazing again. Start by gazing for just a few minutes and then gradually increase your practice. After some months, the visualization will become easy and your meditation will go deeper.
Excerpted from the booklet, Meditation by Sri Swami Satchidananda