There are seven main energy centers (chakras) of the body. These chakras are like spirals of energy, each one relating to the others. Chakras correspond to vital points in the physical body i.e. major plexuses of arteries, veins and nerves. The chakras are thought to vitalise the physical body and to be associated with interactions of a physical, emotional and mental nature. A development in Western practices dating back to the 1940s is to associate each one of the seven chakras to a given color and a corresponding crystal.