It is well known to all that the Vedas are the most revered scriptures of the Vedic Hindus. There are four Vedas known as Rgveda, Yajurveda, Samaveda and Atharvaveda. The Yajurveda has two schools (branches)— Krsnayajurveda and Suklayajurveda.

Our ancestors had memorized and studied the Vedas with a great respect and effort and handed them over generation to generation from time immemorial. Thus the Vedas have come to us without any deviation from their original forms. In our society, there has been a great tradition of dedicated preceptors and disciples who learned and taught the Vedas with correct pronunciation according to the schools they belonged to. In this context, our seers and sages compiled six Vedangas (Limbs of the Vedas) known as Siksa (Phonetics), Kalpa (Rules and descriptions of the Vedic rituals), Vyakarana (Grammar), Nirukta (Etymology), Chhanda (Prosody) and Jyotisa (Astronomy) to clarify the structure, meaning, application, purpose and secret of the Vedas. Moreover many Vedic scholars also created various ancillary works to protect the Vedas in their original forms.

Major works on Siksa (Vedic phonetics) are the Pratigakhyas. In addition to them, Siksas viz. the Saunaka- siksa, the Paniniya-siksa etc. are the guiding works for correct pronunciation. The PratijAastitra is one of the ancillary works which is considered as the supplementary work to the Suklayajurveda-pratisakhya. Thus in the Madhyandiniya Sakha of Suklayajurveda, besides the Suklayajurveda- pratisakhya and the Yajfhavalkyasiksa, the Pratijiasttra is also regarded as an authentic tool to know the correct pronunciation according to Madhyandiniya Sakha tradition.

In this school, the 18 supplementary works of sage Katyayana are famous. Although the PratijAasttra is also considered as a supplementary work of Katyayana, yet it is additional to the 18 supplementary works. Its text is divided into three sections called Kandikas which consist of 10, 8 and 5 Sitras respectively. Few commentaries of the work have been published. Some of them are rare now. Mainly three commentaries written by Anantadeva, Sri Rama Sarma and Nityananda Parvatiya are available today. But it seems there are some_ insufficiencies, obscurities and space for improvement in all of the commentaries. Therefore | have attempted to write both the Sanskrit as well as the Hindi commentary on the work. The Sanskrit commentary explains every Sitra in detail with interpretation of every aspect lucidly on the basis of the Suklayajurveda-pratisakhya and the Yajfhavalkyasiksa. Considerable effort has also been put to clarify the pronunciation of plosive Ya [a] and Va [a] in the commentaries.

I expect that the commentaries will be equally useful for both the scholars and the students of the Vedas and phonetics. I will be highly obliged if the readers provide suggestion for improvement and point out mistakes in the commentaries which will help in furtherance of Vedic studies.