Every deity has a Bija-mantra – a hymn the deity manifests in. ‘AUM’ is the Bija-mantra of all mantras, for it is in ‘AUM’ that a ‘mantra’ finds its way to the deity it is dedicated to, and hence its accomplishment. ‘AUM’ as ‘Pranava’ means ‘that by which (God) is effectively praised’, that is, when a mantra is initiated with ‘AUM’, it becomes the true instrument for praising God and hence reaching Him. In ‘AUM Namah Shivai’, the most potent of Shaiva mantras, ‘AUM’, meaning Sat-Chid-Anand Parabrahma, makes prostration to Lord Shiva absolute whereby the practiser merges into Him. ‘AUM’ is just another name for ‘all pervading Brahman’ and the manifestation of pure consciousness not contained in a form.