The Present book comprises the Pratyaksa Khanda (section on perception), one oe the four sections of Tattvacintamani of Ganesa Upadhyaya (1200 A.D.) This section is divided into twenty-five sub-sections, from mangalavada to savikalpakavada, according to the topics discussed. Herein the author has established the standpoint of the nyaya system, after refuting the doctrines of the opponents, particularly the Buddhists and the Mimamsakas of the Prabhakara school, discussing the factors involved in the process of thinking and exposing their fallacious views. A new methodology and terminology used by the author has entered the other Sastras including grammar which become intelligible after the study of this work. The book has captured the entire intelligentsia of the traditional school of India Besides, on Indian logic as evidenced in the writings of modern scholars like Vidyabhusana, Ingalls, Potter, Guha and Matilal, the present edition of tattvacintamani comes as an indispensable work. The utility of the present work is further enhanced with addition, as introduction, of a summary of the work, reproduced from Vidyabhusana's History of Indian logic.