Sentence:  However, the five-syllable <WSD>mantra</WSD> is unique, for according to Kukai, it unleashes  the power of emptiness already impregnated in each letter as a primeval episode  of the Dharmakaya's cosmic meditation in which he created all sorts of <WSD>mantras</WSD> ... 
Meaning of the word marked with <WSD> tags:  A phrase repeated to assist concentration during meditation. (from 1956)