Yoga is the means of attaining self-realisation by the acts of suspending the manifestations of the mind. There are four aspects of Yoga- (i) Mantrayoga (ii) Hathayoga (iii) Layayoga and (iv) Rajayoga. Out of them, the Mantrayoga is the one which can be instrumental by the support of 'word' (Sabda) consisting the mantra with its meaning and the idol.
Words have power because they are auditory symbols of what they represent. If ordinary words have so much power, those words, which have come down the ages, sanctified their divine associations became veritably receptacles of divine. When Sankaracarya was asked "What is the path which involves little effort but gives great reward, the way which brings the fruits of all disciplines? he replied, "That path is the yoga of chanting".
Mantra is word (or words) which provides a perfect safeguard having destroyed all the fears by (a powerful mental) chanting. Mantra is formed of two words MAN and TRA. Mantras are, infact, meant to bring desired result by their chanting. Since the Word "man" is for concentration of the mind and "tra" is trana i.e. protection.