[MAN'S] actions are divided as regards their object into four classes; they are either purposeless, unimportant, in vain, or good. An action is in vain if the object which is sought by it is not obtained on account of some obstacles. Thus people frequently use the phrase "you have worked in vain" in reference to a person who looks out for some one and cannot find him: or who undertakes the troubles of a journey for his business without profit. Our endeavours and exertions are in vain as regards a patient that is not cured. This applies to all actions which are intended for certain purposes that are not realized. Purposeless are such actions, which serve no purpose at all. Some persons, e.g., do something with their hands while thinking of something else. The actions of the insane and confused are of this kind. Unimportant are such actions by which a trivial object is sought, an object that is not necessary and is not of great use. This is the case when a person dances without seeking to benefit his digestion by that exercise, or performs certain actions for the purpose of causing laughter. Such actions are certainly mere pastimes. Whether an action belongs to this class or not depends on the intention of those who perform it, and on the degree of their perfection. For many things are necessary or very useful in the opinion of one person and superfluous in the opinion of another. E.g., bodily exercise, in its different kinds, is necessary for the proper preservation of health in the opinion of him who understands the science of medicine; writing is considered as very useful by scholars. When people take exercise by playing with the ball, wrestling, stretching out the hands or keeping back the breathing, or do certain things as preparation for writing, shape the pen and get the paper ready, such actions are mere pastimes in the eyes of the ignorant, but the wise do not consider them as unimportant. Useful are such actions as serve a proper purpose: being either necessary or useful for the purpose which is to be attained. This division [of man's actions] is, as I believe, not open to any objection. For every action is either intended for a certain purpose or is not intended; and if intended for a certain purpose, that purpose may be important or unimportant, is sometimes attained and sometimes missed. This division is therefore complete.
After having explained this division, I contend that no intelligent person can assume that any of the actions of God can be in vain, purposeless, or unimportant. According to our view and the view of all that follow the Law of Moses, all actions of God are "exceedingly good." Thus Scripture says, "And God saw everything that he had made, and behold, it was very good" (Gen. 1:31). And that which God made for a certain thing is necessary or [at least) very useful for the existence of that thing. Thus food is necessary for the existence of living beings: the possession of eyes is very useful to man during his life, although food only serves to sustain living beings a certain time, and the senses are only intended to procure to animals the advantages of sensation. The philosophers likewise assume that in Nature there is nothing in vain, so that everything that is not the product of human industry serves a certain purpose, which may be known or unknown to us. There are thinkers that assume that God does not create one thing for the sake of another, that existing things are not to each other in the relation of cause and effect; that they are all the direct result of the Will of God, and do not serve any purpose. According to this opinion we cannot ask why has He made this and not that; for He does what pleases Him, without following a fixed system. Those who defend this theory must consider the actions of God as purposeless, and even as inferior to purposeless actions: for when we perform purposeless actions, our attention is engaged by other things and we do not know what we are doing; but God, according to these theorists, knows what He is doing, and knowingly does it for no purpose or use whatever. The absurdity of assuming that some of God's actions are trivial, is apparent even at first sight, and no notice need be taken of the nonsensical idea that monkeys were created for our pastime. Such opinions originate only in man's ignorance of the nature of transient beings, and in his overlooking the principle that it was intended by the Creator to produce in its present form everything whose existence is possible; a different form was not decreed by the Divine Wisdom, and the existence [of objects of a different form] is therefore impossible, because the existence of all things depends on the decree of God's wisdom. Those who hold that God's works serve no purpose whatever believe that an examination of the totality of existing things compels them to adopt this theory. They ask what is the purpose of the whole Universe? they necessarily answer, like all those who believe in the Creation, that it was created because God willed it so, and for no other purpose. The same answer they apply to all parts of the Universe, and do not admit that the hole in the uvea and the transparency of the cornea are intended for the purpose of allowing the spiritus visus to pass and to perceive certain objects; they do not assume that these circumstances are causes for the sight; the hole in the uvea and the transparent matter over it are not there because of the sight, but because of the Will of God, although the sense of sight could have been created in a different form.
There are passages in the Bible which at first sight we might understand to imply this theory. E.g., "The Lord has done whatever he pleased" (Ps. 135:6); "His soul desired it and he made it" (Job 23:13); "Who will say unto you, What to do?" (Eccles. 8:4). The meaning of these and similar verses is this: whatever God desires to do is necessarily done; there is nothing that could prevent the realization of His will. The object of His will is only that which is possible, and of the things possible only such as His wisdom decrees upon. When God desires to produce the best work, no obstacle or hindrance intervenes between Him and that work. This is the opinion held by all religious people, also by the philosophers; it is also our opinion. For although we believe that God created the Universe from nothing, most of our wise and learned men believe that the Creation was not the exclusive result of His will; but His wisdom, which we are unable to comprehend, made the actual existence of the Universe necessary. The same unchangeable wisdom found it as necessary that non-existence should precede the existence of the Universe. Our Sages frequently express this idea in the explanation of the words, "He has made everything beautiful in his time" (Eccles. 3:11), only in order to avoid that which is objectionable, viz., the opinion that God does things without any purpose whatever. This is the belief of most of our Theologians: and in a similar manner have the Prophets expressed the idea that all parts of natural products are well arranged, in good order, connected with each other, and stand to each other in the relation of cause and effect; nothing of them is purposeless, trivial, or in vain; they are all the result of great wisdom. "O Lord, how manifold are your works! in wisdom you have made them all: the earth is full of your riches" (Ps. 104:24); "And all his works are done in truth" (ibid. 4) The Lord by wisdom has founded the earth" (Prov. 3:19). This idea occurs frequently; there is no necessity to believe otherwise; philosophic speculation leads to the same result; viz., that in the whole of Nature there is nothing purposeless, trivial, or unnecessary, especially in the Nature of the spheres, which are in the best condition and order, in accordance with their superior substance.
Know that the difficulties which lead to confusion in the question what is the purpose of the Universe or of any of its parts, arise from two causes: firstly, man has an erroneous idea of himself, and believes that the whole world exists only for his sake; secondly, he is ignorant both about the nature of the sublunary world, and about the Creator's intention to give existence to all beings whose existence is possible, because existence is undoubtedly good. The consequences of that error and of the ignorance about the two things named, are doubts and confusion, which lead many to imagine that some of God's works are trivial, others purposeless, and others in vain. Those who adopt this absurd idea that God's actions are utterly purposeless, and refuse to consider them as the result of His wisdom, are afraid they might otherwise be compelled to admit the theory of the Eternity of the Universe, and guard themselves against it by the above theory I have already told you the view which is set forth in Scripture on this question, and which it is proper to accept. It is this: it is not unreasonable to assume that the works of God, their existence and preceding non-existence, are the result of His wisdom, but we are unable to understand many of the ways of His wisdom in His works. On this principle the whole Law of Moses is based; it begins with this principle: "And God saw all that He had made, and, behold, it was very good" (Gen. 1:31); and it ends with this principle: "The Rock, perfect is His work" (Deut. 32:4). Note it. When you examine this view and that of the philosophers, taking into consideration all preceding chapters which are connected with this subject, you will find that there is no other difference of opinion as regards any portions of the Universe, except that the philosophers believe in the Eternity of the Universe and we believe in the Creation. Note this.
[Moreh Nevuchim 3-25]
