Since furnishing excerpts from the book will make this post unnecessarily lengthy, I am giving below only some of the salient observations summarized as best as I could. Portions from the book are given within quotes.
Out of 115 works (15 bhAshyas and 100 prakaraNa granthas) generally believed to be of Sankara, 12 as under are those which constitute the prasthAnatraya:
1. eeSAvAsya upanishadbhAshya
2. kEnopanishadbhAshya
3. kaThopanishadbhAshya
4. praSnopanishadbhAshya
5. muNDakopanishadbhAshya
6. mANDUkyopanishadbhAshya
7. taittiriyopanishadbhAshya
8. aitarEyopanishadbhAshya
9.chAndogyopanishadbhAshya
10. br^hadAraNyakopanishadbhAshya
11. bhagavadgitA bhAshya
12. brahmasUtra bhAshya
"Tradition dares not utter a word of doubt about their authorship, although interpolations have crept into them in the efflux of time."
Out of the 100 prakaraNa granthas, while some are Sankara's works, many do not look like so. Others must have written these using his name and since the words शंकराचार्य विरचितः appears, many generations have thought all of them to be real works of the Acharya.
Sankara is known mainly as bhAshyakAra or commentator and the bhAshyas are his main works, the others, if any, being secondary only in importance. His bhAshyas contain his immortal message, viz., advaita and these are considered the last word in advaita philosophy. Hence if a prakaraNa text makes a departure from the line of his bhAshyas, there is no reason why such a prakaraNa should not be summarily rejected as not Sankara's work, as it is inconceivable that the Acharya would have said one thing in his bhAshyas and a very different, or contrary view in a prakaraNa.
It is relevant to note, in this context, that the method used in most hindu religious texts is to prefix 'vyAsa yvAca', 'nArada uvAca', 'Suka uvAca', etc., and Swami Dayananda Saraswati has, in his satyArthaprakASikA, opined that that was the method used to make the illiterate, ignorant, devotees to believe that these messages had really come from some very high and supernatural sources, and hence have to be treated with unquestioned belief and reverence. A somewhat similar position obtains in the case of some of the texts purported to be of Sankara. There were many great scholars in the Sankara lineage and their works also bear the words शंकराचार्य विरचितः without any more details and so could have been mistaken for the Acharya's works.
Shri Panoli then analyses several texts of this class. His findings are summarised below.
1. SvEtASvataropanishadbhAshya:
Panoli holds that the entire work is of some one other than Sankara, on the basis of the following:
a) The extra-ordinarily long introduction, uncharacteristic of Sankara.
b) The acceptance of sAnkhya and yoga as means of liberation in this treatise (sv. bh.-VI.13) whereas Sankara has unambiguously in more than one context in the other commentaries, e.g., SAnkarabhAshya on brahmasUtra (II,1-2-3), br^hadAraNyaka bhAshya, geetA bhAshya (XVIII.19), vivEkacUDAmaNi (56). Sankara clearly states in his sUtra bhAshya that द्वैतिनो हि सांख्या योगाश्च नात्मैकत्वदर्शिनः । (Those who follow sAmkhya and yoga are but dualists. They are not the perceivers of the unity of the Self.)
Further, the first two lines of sv. up.VI.13 appear in kaThopanishad (II,2-13) with the word 'nityAnAm' in the former changed to 'anityAnAm' which Sankara has commented in clear, logical and his usually recognized style, whereas, the commentary of the equivalent stanza in sv. up. is comparatively pedestrian.
A similar difference in style is seen in sv. up. IV.6 and muNDaka up. III,1-1 (both identical) the latter being the original source for the former.
For those who doubt the above conclusion Panoli's reply is as under:
" When the advaita philosophy of Sri Sankara won universal recognition, the Yoga and Samkhya systems of Patanjali and Kapila respectively, the Nyaya system of Gautama, the Vaiseshika system of Kanada and the Karmamimamsa of Jaimini could not hold ground as before. Even the logical system of Gautama which is more to the purpose than the other four was found to be wanting from the point of view of reaching the ultimate goal. The Bhakti cult also began to shake, for in the philosophy of the Acharya Devipooja or Sakti-worship or idol worship has no place at all. Naturally the followers of every other system and cult became aware of their weaknesses. How to stem the tide? The leaders of every other system and cult soon began to snatch every opportunity to interpolate 'little-bits' of their own philosophical principles in Acharya's works so carefully that none would be able to detect it, so that the followers and worshipers of the Acharya might think that he too was a sympathizer of their causes. That is how we find in the name of the Acharya a bhashya itself on the Svetasvatara Upanishad to make the readers believe that Samkhya and Yoga systems are capable of leading one to liberation. But we have seen already how both Badarayana and Sri Sankaracharya have totally refused to accept the claims of those two systems. In the coming chapters will be shown how the other systems too made attempts to infuse their theory into the Sankarabhashya and into the various Prakarana-texts composed by him. The Bhakti cult too was no exception. The votaries of that cult also invented many things for interpolating in the Acharya's works. As already pointed out above, there is not a single sentence in the Prasthanatraya-bhashya which tends to show Bhakti as having at least a remote claim to be a means of attaining emancipation. Definitely, the Bhakta-loka would never believe it, for they cannot bear to think of it. They would not also be prepared to examine the bhashya..."
2. vishNusahasranAmabhAshya:
vishNusahasranAma (vsn) is adhyAya 149 of the anuSAsanaparva of the mahAbhArata, consisting of 142 verses. The 13 initial verses are introductory passages. The bhAshya under consideration devotes an unduly long number of printed pages (in the Gita Press, Gorakhpur version 16-1/2) for the 10th. verse alone. Similarly the first name "visvam" is explained in 8-3/4 pages. When one considers the short, pithy introductions (23 sentences to the geetA, 4 sentences to praSnopanishadbhAshya) and made it clear in almost all his major works that he was giving only a brief commentary, such tediously long introduction and equally tedious treatment of a few names and stanzas, will definitely reveal that this too is not the work of the Acharya.
Further some of the names in vsn appear here and there in the Prasthanatraya-bhashyas as well, but the meaning/s assigned to those terms therein are widely different from those appearing in vsn bhashya.
Examples are-
a. prabhu - swAmi (geetA IX-18, IC-24); Atman (geetA V)--कालभेदमनादृत्य सन्मात्रप्रतियोगिकमैश्वर्यमस्येति प्रभुत्वम् (prabhu because of His greatness consisting in His absolute existence without being associated with different periods of time), सर्वासु क्रियासु सामर्थ्यातिशयात् प्रभुः(prabhu because of His being exceedingly powerful in all the acts), प्रकर्षेण भवनात् प्रभुः (prabhu because He exists most gloriously)-(all three in vsn bhashya)
b. eeSvaraH has been explained as निरुपाधिकमैश्वर्यमस्येति (of unlimited glory) in vsn bhAshya and, if the author could not summarize the commentary on the word in less than 8-3/4 pages, it is surprising that he could explain the word eeSvara, which is very important in philosophy, in such a condensed form! Sankara, on the contrary, explains the word eeSa as ईशा ईष्ट इतीष्ट् तेनेशः। ईशिता परमॆश्वरः। (He who commands is eeT; eeSA is the Supreme Lord, the Supreme self of everything.)in eeSAvAsyopanishadbhAshya, as नित्यशुद्धबुद्धमुक्तस्वभावः ईश्वरः (eeSvara is eternal, pure, intelligent and free by nature.) in muNDakabhAshya and the geetA bhAshya. The difference in the case of vsn bhAshya is obvious.
c. The word skanda स्कन्दः occurs only once in the whole of the ten principal upanishads (in chAndogya) and there sanatkumAra alone is meant which the Acharya also points this out. In geetA X-24, Acharya has explained skanda as dEvasEnApati. However in vsn bhAshya this word is interpreted as स्कन्दत्यमृतत्वरूपेण गच्छति वायुरूपॆण शोशयतीति वा स्कन्दः (He who flows in the form of nectar, or dries up everything as wind is skanda.) If the author was the Acharya he would have not used such a different meaning or at least explained as to why the difference came, especially since the name nArAyaNa has been explained in all possible ways in the vsn bhAshya.
The lack of the touch of genius and creativity observed in vsn bhAshya definitely points out that its author could not have been the Acharya.
Sankara in his geetA bhAshya has not explained यज्ञानाम् जपयज्ञोस्मि (Of yajnas I am japa. -X-26). Why this? Most probably because he did not consider japa as a necessary instrument for the realization of the Supreme.
Sankara has , in the br^hadAraNyakopanishadbhAshya (V-14) stated प्रयोक्तृगयत्राणात् गायत्रि (because it protects the organs of its reciter it is gAyatri.) but also follows with the statement न चान्येषाम् छन्दसाम् प्रयोक्तप्राणत्राणसामर्थ्यम् (And the metres other than gAyatri do not have the power to protect the prANa of the reciter.) This indicates that Sankara accepted, at best, only the recitation of the gAyatri and no other mantra or Sloka as a desirable means to liberation. He has not even once mentioned nAma japa in his entire prasthAnatrayabhAshya. Will such a person comment on vsn? It is an unauthentic work being attributed to Samkara.
(To be continued)