Dikshitar travelled widely, entering into philosophical disputations and controversaries in many centres of learning. He had the rare good fortune of being revered and patronised in his own life-time by kings of Vellore, Tanjore, Vijayanagara and Venkatagiri.
Dikshitar threw himself heart and soul into this mission for several years and often had to face grave personal danger, which he did with courage and faith. He preached, organised and wrote incessantly, enlisting the cooperation of several enlightened monarchs. He undertook frequent travels and challenged his adversaries to open disputation, as was the custom of those days. He brought to bear on his widespread activities, his resourceful personality and created an atmosphere of tolerance and goodwill, in the place of the prevailing antipathies and narrow-mindedness.
In addition to his poetic skills and achievements on the philosophical propagations and Saivite missionary work, Dikshitar was a great Siddha-yogi. One of his yogic experiments was as great as it was thrilling. In the later years of his life, he was subject to attacks of colic pain. He was convinced that it was due to his Prarabdha and past karma. Whenever he wanted to meditate deeply or worship the Almighty, he made a bundle of his towel and put it in front of him. By his yogic power he transferred his malady to the towel and sat in meditation. His disciples watched the towel jumping about the place. To them he explained later that he transferred his ailment which was in the form of an evil spirit to the cloth and then took it back soon after his meditation was over.
About his mystic devotion, there is another story that is related to his work called Atmarpana-stuti. In this small work of fifty stanzas he makes the inner self melt as it were by his exquisite mystic poetry. We can see here the profound maturity of true devotion to the Supreme. It reflects the inner mental state of a great devotee, in whom the ego has become fully extinct. There is a traditional account of how this work came to be written. It appears once he wanted to test the maturity of his own devotion to the Lord. Hence he swallowed the juice of the `datura' fruit, which introduces intoxication, and told his disciples that they should write down whatever he says, during the stage when his consciousness was disturbed. In the stage of inebriation generally all suppressed ideas would find release and come out into the open. And in his case it was the Atmarpana-stuti that came out. It is therefore also called Unmatta-panchasati.
He wrote the Chatur-mata-sara to illustrate the philosophical thoughts of the four prominent schools of interpretation of Brahma sutras. The Naya-manjari deals with advaita, the Naya-mani-mala with Srikanta mata, the Naya-mayukha-malika with Ramanuja's philosophy, and the Naya-muktavali with Madhva's philosophy. His remarkable catholicity of outlook, his thoroughness in writing, his impartiality, his unerring sense of values, and his concern for truth are all so evident in these writings that the Vaishnavas have adopted the Naya-Mayukha-Malika as their manual for study, and the Madhvas the Naya-Muktavali.
Among the Vedantic works of Appayya Dikshitar, the Siddhanta-lesha-sangraha is most famous. In this elaborate and original treatise, he brings together in one place, all different dialectical thinking belonging to the advaitic school. Traditional students of Vedanta begin their study of Vedantic commentaries only after studying this Siddhanta Lesha sangraha. All the different views of different subschools of advaita, like those of `eka-jiva-vada', `nana-jiva-vada', `bimba-pratibimba vada' `sakshitva-vada' etc. are all discussed and the contrary views properly explained in this work with Appayya Dikshitar's masterly touch. And in his characteristic eclectic style, he answers the question "How can there be contradictory views among the advaita acharyas themselves on the same point?" He says: All the masters agree in affirming the unity of the soul and the unreality of the phenomenal world. For the world of fiction different explanations are given according to the ingenuity of each acharya. What if different explanations are given for a mere fiction?
It is a Vedantic work, an extremely readable commentary on the very difficult commentary called Kalpataru by an advaitic teacher named Amalananda. That Kalpataru is itself a commentary on Bhāmatī by Vācaspati Miśra, which in turn is the famous commentary on the Sutra-Bhashya of Adi Shankara.
While the Parimala follows the advaitic approach, Dikshitar has written another commentary Sivaarka-mani-deepika on the Brahmasutras. But this is written from the point of view of Siva-visishtadvaita.. These two works – Sivaarka-mani-deepika and Parimala – are his magnum opus both in bulk and importance. Though both are commentaries on the Brahma sutra, Parimala aligns itself to the advaitic interpretation while the other work expounds the Sivadvaita philosophy of Srikanta-acharya. Dikshitar's patron, King Chinna Bomma Nayak of Vellore made endowments for the maintenance of a college of 500 scholars who studied Sivaarka maniDipika under Sri Dikshitar himself, thus equipping themselves for the Saivite propaganda work, which had been organised with a view to stemming the tide of Vaishnavite attacks and encroachments.
Dikshitar graphically describes dvaita as the lowest step, vishishtadvaita as the middle step and sivadvaita and advaita which are very close to each other as the highest steps. He makes it clear in his work that Srikantha-Bhashya on the Brahmasutra has been written in very close approximation to the trend of thought of Adi Sankara in his own bhashya. Srikanta, according to Dikshitar, propagated his cult on the understanding that sagunopasana (Worship of name and form) is only the first step to nirgunopasana (Propitiation of the nameless and formless), and that it was the real intention of Srikanta that the final truth lies only in Shuddhadvaita. Dikshitar's great dialectical skill is fully reflected in the work called 'Anandalahari chandrika', where he tries to narrow down the differences between the apparently divergent schools of thought and tries to show that the advaita of Sankara is the real eternal truth to which all others try to approximate.