Anan expounded his views concerning religious commandments and prohibitions in three works, one of which was a commentary on the Pentateuch, certainly the very first of all productions of this class. Anan's works have not survived the lapse of time; the original character of Karaism is thus enveloped in complete obscurity. This only is clear, that in his hostility to the Talmud the founder of the Karaite sect increased rather than lessened the religious duties of life, enforced many observances which time and custom had long abolished, and in his blind eagerness to change the Talmudical exposition of the Law, often fell into ridiculous exaggerations. He made use of the Talmudical, or more properly the Mishnaic rules of interpretation, and with their help considered himself entitled, equally with the old teachers (of the Mishna), to deduce new laws of religion. The most important alterations were those made in the dates of the festivals, the Sabbath, in the laws of marriage, and the dietary regulations. Anan abolished the fixed calendar, which had been established in the middle of the fourth century; but finding no grounds in the Bible for this innovation, he was obliged to refer back to the time of the Second Temple and the Tanaites. As in former times, the beginning of every month was to be fixed by observation of the new moon. The leap years were not to follow in a regular series, according to the nineteen-years cycle, but were to be determined by repeated examination of the condition of the crops, especially at the time of the ripening of the barley. This was not so much an absolute innovation as a renewal of a method of regulating the festivals, the untenableness of which in the state of dispersion of the Jewish nation is evident. This variability of the calendar offered but little difficulty to Anan and his followers in Palestine, but it shows little foresight for the future. As had been formerly done by the Sadducees, Anan fixed the Feast of Pentecost fifty days after the Sabbath following the Passover.