In Sanskrit there are thirteen vowels and thirty-five consonants. The vowels are a, a, i, i, u, u, r, r, l, e, ai, o, au, and the consonants are ka, kha, ga, gha, etc. Amongst the consonants, the first twenty-five letters are called the sparsas. There are also four antah-sthas. Of the usmas there are three ss, called talavya, murdhanya and dantya. The musical notes are sa, r, ga, ma, dha, and ni. All these sound vibrations are originally called sabda-brahma, or spiritual sound. It is said, therefore, that Brahma was created in the Maha-kalpa as the incarnation of spiritual sound. The Vedas are spiritual sound, and therefore there is no need of material interpretation as they are, although they are symbolically represented with letters which are known to us materially. In the ultimate issue there is nothing material because everything has its origin in the spiritual world. The material manifestation is therefore called illusion in the proper sense of the term. For those who are realized souls there is nothing but spirit.