This is an interesting book that makes a fairly extensive analysis of Gita and concludes that Bhagavad-Gita was written by three different authors over a period of several centuries, and these authors are Vyasa, Vaisampayana and Souti.
A summary of this book is as follows: The author observes certain textual difficulties and contradictions in Gita, and cites the following examples:
1. The repetition of the topics such as Jnana in Gita verses, 4.33-42; 7.16-19; 13.5-11; 18.18-22; and 18.70; the concept of Brahman in verses 5.20-26; 6.27-28; 7.29; 8.3-28; 13.12-17 and 18.50-53. And the contradictions found in Gita about the principles of Sankhya, Vedanta and yoga philosophy.
2. Supreme Being is described in different terms such as Purusha, Brahman, Ishvara, Paramatman, kshtrajna, akshara, and asat
3. Krishna Identifies himself as Brahman, Purusha and Tat in the third person-singular, but in chapters VII, IX, X, XI, XII, and XVI it is in the first person-singular. In chapter XII it is mainly in the third person singular form. Other chapters use a combination of the two.
4. Human beings and their activities are classified into sattvic, rajas and tamas in chapters XIV, XVII and XVIII but in chapter XVI it becomes a two fold classification like daivi and asuri.
5. The central theme of Gita sometimes is difficult to comprehend; it appears to be sanyasa or Jnana or bhakti, self-realization or mystical experience.
The author suggests the he came up with the idea of three authors as a result of an intensive textual study of the Gita with regard to its structure, grammar, exposition, style, diction, terminology, objectives and philosophy. Each author presented the metaphysical concepts that existed or evolving around his time mainly for readers of his time. The first author composed the first six chapters (first sextet) some time before the 6th century B.C. The second author added six more chapters (second sextet) and they form portions of the present VIII, XIII, XIV, XV, XVII and XVIII chapters. The third author added six more chapters (third sextet) in the middle of the poem and shifted the poems of the second author to the final sextet. His new chapters are VII, IX to XII and XIV. The author contends that the original author accepted the principles of Sankhya philosophy of his time, the immortality of soul, its aloofness from matter and senses, importance of spiritual knowledge, the psychological attitude of renunciation, the value of self realization, and the supremacy of Brahman. The Sankhya philosophers deduced absolute renunciation from these tenets, but the author of the first Gita deduced yoga (spiritual activism) disinterested in action or devotion to duty. The first author used the materials of Sankhya to propose his theory of ethics of action. He reduced the conflict between knowledge and action between Sankhya renunciation and the Vedic karma by creating Karma-yoga.
The second author added the new concepts to Sankhya and mimamsa of his time (about 2 or 3 century after the first author); concepts of Jnana, Kshetra-Kshetragna, Prakriti-Purusha, and Triguna-bheda. He did not create new philosophy, but faithful in reproducing Sankhya with impartiality and scholastic objectivity. The abstract theory of karma yoga is supplemented with three levels of existence, the sattvic, rajas and tamas. After about two centuries, the third author introduced the bhakti principle, and the worship of Lord Vasudeva-Krishna as the Godhead. He also extended the Vedanta philosophy that was developed at his time and brought about unification of Sankhya and Vedanta along with yoga philosophy, and he tried to sublimate the primitive traditional forms of worship into one incarnation of the Supreme Being. He tried to achieve conviction not with convincing argument but with the combined weapons of faith, mysticism, divinity, supernatural powers, admiration, superhuman forms, illusion and visions. This author is also a superb stylist and composer of great poetry. He uses new words and phrases not used by previous authors. There is a rhythm, grace and elegance in his style. The most sublime verses are those that describe God's relationship with people. The author reaches highest peak of imagination and grace in chapter XI. His description of the abstract nature of time and space is astounding. The third poet made bhakti as the main theme of his redaction.
The author of this book proposes an interesting theory but is not accepted in the academic world or by the seekers spiritual knowledge. Certain textual difficulties and contradictions could be resolved on the assumption of the oversight of a single author and or it could be dealing with several subject matters such as Sankhya or Vedanta or Yoga philosophy may cause some confusion and its hermeneutics.