We must admit that very little is known about the first development of Indian logic and particularly about Buddhist logic before Diṅnāga. If we take the best manuals of Indian logic now available, such as those by Suali, Vidyābhūṣāṇa, Keith, or the most comprehensive Histories of Indian philosophy like those of Dāsgupta and Rādhākrishna we shall easily recognize that the data contained therein are far from being satisfactory; more than that, they are also very often wrong. In fact, almost the only source from which their statements are derived is the book by Sugiura, who certainly had the merit of giving the first account of Indian logic as preserved in Chinese sources, but, being himself absolutely without knowledge of orthodox nyāya and of Sanscrit, is in his statements and in his translations very often misleading.