The Five Sounds

Now, The Five Vowels is being written.

Having bowed to the Support of the Universe, the observer of the worlds visible and invisible, and to Prajapati A Vedic deity associated with creation and the protection of life., the Lord of the World, the science of the Five Vowels shall now be expounded. || 1 ||

The vowel A, the vowel I, the vowel U, and indeed the vowel E—and also the vowel O—these five are the vowels declared by the great sages. || 2 || original: A-kāra, I-kāra, U-kāra, Ai-kāra, O-kāra; while the Sanskrit alphabet has many more vowels, this specific system of Svara Śāstra (the science of sound-omens) simplifies them into these five categories for the purpose of divination.

A, I, U, E, O: these are the vowels.