Guide for the Perplexed, by Moses Maimonides, Friedländer tr. [1904], at sacred-texts.com
You must consider, when reading this treatise, that mental perception, because connected with matter, is subject to conditions similar to those to which physical perception is subject. That is to say, if your eye looks around, you can perceive all that is within the range of your vision: if, however, you overstrain your eye, exerting it too much by attempting to see an object which is too distant for your eye, or to examine writings or engravings too small for your sight, and forcing it to obtain a correct perception of them, you will not only weaken your sight with regard to that special object, but also for those things which you otherwise are able to perceive: your eye will have become too weak to perceive what you were able to see before you exerted yourself and exceeded the limits of your vision.
The same is the case with the speculative faculties of one who devotes himself to the study of any science. If a person studies too much and exhausts his reflective powers, he will be confused, and will not be able to apprehend even that which had been within the power of his apprehension. For the powers of the body are all alike in this respect.
The mental perceptions are not exempt from a similar condition. If you admit the doubt, and do not persuade yourself to believe that there is a proof for things which cannot be demonstrated, or to try at once to reject and positively to deny an assertion the opposite of which has never been proved, or attempt to perceive things which are beyond your perception, then you have attained the highest degree of human perfection, then you are like R. Akibha, who "in peace entered [the study of these theological problems], and came out in peace." If, on the other hand, you attempt to exceed the limit of your intellectual power, or at once to reject things as impossible which have never been proved to be impossible, or which are in fact possible, though their possibility be very remote, then you will be like Elisha Aḥer; you will not only fail to become perfect, but you will become exceedingly imperfect. Ideas founded on mere imagination will prevail over you, you will incline toward defects, and toward base and degraded habits, on account of the confusion which troubles the mind, and of the dimness of its light, just as weakness of sight causes invalids to see many kinds of unreal images, especially when they have looked for a long time at dazzling or at very minute objects.
Respecting this it has been said, "Hast thou found honey? eat so much as is sufficient for thee, lest thou be filled therewith, and vomit it" (Prov. xxv. 16). Our Sages also applied this verse to Elisha Aḥer.
How excellent is this simile! In comparing knowledge to food (as we observed in chap. xxx.), the author of Proverbs mentions the sweetest food, namely, honey, which has the further property of irritating the stomach, and of causing sickness. He thus fully describes the nature of knowledge. Though great, excellent, noble and perfect, it is injurious if not kept within bounds or not guarded properly; it is like honey which gives nourishment and is pleasant, when eaten in moderation, but is totally thrown away when eaten immoderately. Therefore, it is not said "lest thou be filled and loathe it," but "lest thou vomit it." The same idea is expressed in the words, "It is not good to eat much honey" (Prov. xxv. 27); and in the words, "Neither make thyself over-wise: why shouldst thou destroy thyself?" (Eccles. vii. 16); comp. "Keep thy foot when thou goest to the house of God" (ibid. v. 1). The same subject is alluded to in the words of David, "Neither do I exercise myself in great matters, or in things too high for me" (Ps. cxxxi. 2), and in the sayings of our Sages: "Do not inquire into things which are too difficult for thee, do not search what is hidden from thee: study what you are allowed to study, and do not occupy thyself with mysteries." They meant to say, Let thy mind only attempt things which are within human perception; for the study of things which lie beyond man's comprehension is extremely injurious, as has been already stated. This lesson is also contained in the Talmudical passage, which begins, "He who considers four things," etc., and concludes, "He who does not regard the honour of his Creator"; here also is given the advice which we have already mentioned, viz., that man should not rashly engage in speculation with false conceptions, and when he is in doubt about anything, or unable to find a proof for the object of his inquiry, he must not at once abandon, reject and deny it; he must modestly keep back, and from regard to the honour of his Creator, hesitate [from uttering an opinion) and pause. This has already been explained.
It was not the object of the Prophets and our Sages in these utterances to close the gate of investigation entirely, and to prevent the mind from comprehending what is within its reach, as is imagined by simple and idle people, whom it suits better to put forth their ignorance and incapacity as wisdom and perfection, and to regard the distinction and wisdom of others as irreligion and imperfection, thus taking darkness for light and light for darkness. The whole object of the Prophets and the Sages was to declare that a limit is set to human reason where it must halt. Do not criticise the words used in this chapter and in others in reference to the mind, for we only intended to give some idea of the subject in view, not to describe the essence of the intellect: for other chapters have been dedicated to this subject.