Guide for the Perplexed, by Moses Maimonides, Friedländer tr. [1904], at sacred-texts.com
IN comparing the objections raised against one theory with those raised against the opposite theory, in order to decide in favour of the least objectionable, we must not consider the number of the objections, but the degree of improbability and of deviation from real facts [pointed out by the objections]; for one objection may sometimes have more weight than a thousand others. But the comparison cannot be trustworthy unless the two theories be considered with the same interest, and if you are predisposed in favour of one of them, be it on account of your training or because of some advantage, you are too blind to see the truth. For that which can be demonstrated you cannot reject, however much you maybe inclined against it; but in questions like those under consideration you are apt to dispute [in consequence of your inclination). You will, however, be able to decide the question, as far as necessary, if you free yourself from passions, ignore customs, and follow only your reason. But many are the conditions which must be fulfilled. First you must know your mental capacities and your natural talents; you will find this out when you study all mathematical sciences, and are well acquainted with Logic. Secondly, you must have a thorough knowledge of Natural Science, that you may be able to understand the nature of the objections. Thirdly, you must be morally good. For if a person is voluptuous or passionate, and, loosening the reins, allows his anger to pass the just limits, it makes no difference whether he is so from nature or from habit, he will blunder and stumble in his way, he will seek the theory which is in accordance with his inclinations. I mention this lest you be deceived; for a person might some day, by some objection which he raises, shake your belief in the theory of the Creation, and then easily mislead you: you would then adopt the theory [of the Eternity of the Universe) which is contrary to the fundamental principles of our religion, and leads to "speaking words that turn away from God." You must rather have suspicion against your own reason, and accept the theory taught by two prophets who have laid the foundation for the existing order in the religious and social relations of mankind. Only demonstrative proof should be able to make you abandon the theory of the Creation: but such a proof does not exist in Nature.
You will not find it strange that I introduce into this discussion historical matter in support of the theory of the Creation, seeing that Aristotle, the greatest philosopher, in his principal works, introduces histories in support of the theory of the Eternity of the Universe. In this regard we may justly quote the saying: "Should not our perfect Law be as good as their gossip?" (B. T. Baba batra, 115 b). When he supports his view by quoting Sabean stories, why should we not support our view by that which Moses and Abraham said, and that which follows from their words?
I have before promised to describe in a separate chapter the strong objections which must occur to him who thinks that human wisdom comprehends fully the nature of the spheres and their motions: that these are subject to fixed laws, and capable of being comprehended as regards order and relation. I will now explain this.