Rabbi Berel Wein giving a lecture on the ZOHAR (Book of Splendor, published in 1290 by Rabbi Moshe DeLeon in Spain). The lecture took place at Yeshivat AISH HATORAH.
I do agree with the statement of Rabbi Yaakov of Emden. Furthermore, the wife of Rabbi DeLeon said after her husband's death that he (her husband) wrote the book. When asked why, Mrs DeLeon said that a book written by an author such as Rabbi Shimon sells much better. Further, Mrs DeLeon justified her husband by saying that they desperately needed the income from the book in order to pay their rent and this is the reason why Rabbi Moshe DeLeon claimed that the true other was Rabbi Shimon. Let's call it one of the first public relation campaigns.:-)