The Twelver Shi'a says that the imam Ja'far al-Sadiq disinherited his son Isma'il for drunkenness and gave the succession to another, Musa al-Kazim. Others argued that once an imam always an imam and continued to recognize Isma'il. Prof. Bernard Lewis has pointed out that there are hints at something worse than drunkenness, perhaps heresy. Sunni writers represent the Isma'ilis as godless with seven stages of initiation leading up to a repudiation of all religion but this is due to a misunderstanding and to the belief that every secret doctrine must be evil. Till recently, the Isma'ilis kept their books hidden from the profane and this secrecy still persists but some of their books have now been published though the texts are usually corrupt and need the oral tradition of interpretation to explain them fully.