The authorship and date of writing are unknown, and there is evidence that the surviving manuscripts are not original and have been modified in their history but were most likely completed in the available form between 2nd-century BCE to 3rd-century CE. Olivelle states that the surviving manuscripts of the Arthashastra are the product of a transmission that has involved at least three major overlapping divisions or layers, which together consist of 15 books, 150 chapters and 180 topics. The first chapter of the first book is an ancient table of contents, while the last chapter of the last book is a short 73 verse epilogue asserting that all thirty two "Yukti" – elements of correct reasoning methods – were deployed to create the text.