Mandala is a circle which is a device for the Tantric meditation. It is a visual aid for concentration and introversive meditation leading to the attainment of insights and to activation of forces culminating in Siddhi supernatural forces. The Mandala is the graphic representation of this process. It is not only theoretical but practical also as an operational scheme involving a clear plan for practical realization of the process within oneself. It thus becomes an instrument (Yantra).