Thoth was the ibis-headed god of writing and patron of the the scribal arts. His cult centre was at Hermopolis where many thousands of ibis were mummified. Originally the god of the moon, Thoth was often depicted with a lunar crescent or disc on his head. His sacred animal, the baboon, was often represented sitting on Thoth's head or shoulders directing the work of the scribes. Thoth was the inventor of speech, mathematics and the calendar and precided over all forms of measurement. He was the accountant of the gods and secretary to Ra. As Lord of Magic he wrote a 42 volume book in which was written the entire wisdom of the world and taught Isis, The Great Enchantress, many of the spells she knew. Thoth was the upholder of justice and the searcher after truth. In the Judgement Hall of Osiris he is seen beside the balance, with his palette and reed, ready to record the result of the weighing of the heart.