By this method, Grotefend had correctly identified each king in the inscriptions, but his identification of the value of individual letters was still quite defective, for want of a better understanding of the Old Persian language itself. Grotefend only identified correctly eight letters among the thirty signs he had collated. However groundbreaking, this inductive method failed to convince academics, and the official recognition of his work was denied for nearly a generation. Although Grotefend's Memoir was presented to the Göttingen Academy of Sciences and Humanities on September 4, 1802, the Academy refused to publish it; it was subsequently published in Heeren's work in 1815, but was overlooked by most researchers at the time.