He wrote his work on the philosophy of religion, Emunoth we-Deoth, in 934. Its object was to oppose and correct the erroneous views of his contemporaries as to the meaning of Judaism; on the one hand were the opinions of the unbelievers, who degraded it; and on the other, those of the ignorant people, who condemned all speculating on religious subjects as involving a denial of God. "My heart is sad," he writes in the introduction, "by reason of my people, who have an impure belief and a confused idea of their religion. Some deny the truth, clear as daylight though it be, and boast of their unbelief. Others are sunk in the sea of doubt, and the waves of error close over their heads, and there is no swimmer strong enough to stem the tide and rescue them. As God has given me the capacity of being useful to them, I consider it my duty to lead them to the right path. Should any one object and ask, 'How can we attain a true belief through philosophic thought, when many consider this as heresy and unbelief?' I would reply, 'Only the stupid do so, such as believe that every one who goes to India will become rich, or that the eclipse of the moon is caused by a dragon's swallowing the disc of the moon, and similar things.' Such people need not trouble us. Suppose, however, that one were to quote the warning of the Talmud against philosophical speculation, 'If any one searches into the mystery of eternity and space, such a person does not deserve to live,' we should reply that the Talmud could not have discouraged right thinking, since Scripture encourages us to it. The warning of the sages was intended to keep us only from that one-sided speculation which does not take into account the truth of Scripture. Limitless speculation can give rise only to error, and should it even eventually lead to truth, it has no firm foundation, because it rejects revelation, and puts doubt into its place. But when philosophy works hand in hand with faith, it cannot mislead us. It confirms revelation, and is in a position to refute the objections that are made by unbelievers. The truth of revealed Judaism may be premised, since it was confirmed through visible signs and miracles. Should, however, some one object that if speculation arrives at the same conviction as revelation, the latter is superfluous, since human reason could arrive at the truth without divine interposition, I should reply that revelation is necessary, inasmuch as, without it, men would have to go a long way round to reach clearness through their own thought. A thousand accidents and doubts might hinder their progress. God, therefore, sent His messengers to us in order to save us all this trouble. We thus have a knowledge of Him direct, confirmed by miracles."