Emil Schürer writes (The Literature of the Jewish People in the Time of Jesus, pp. 329-331):

While this shorter explanation in a catechetical form [Questions and Answers on Genesis] was intended for more extensive circles, Philo’s special and chief scientific work is his large allegorical commentary on Genesis, Νομων ιερων αλληγοριαι (such is the title given it in Euseb. Hist. eccl. ii. 18. 1, and Photius, Bibliotheca cod. 103. Comp. also Origen, Comment. in Matth. vol. xvii. c. 17; contra Celsum, iv. 51). These two works frequently approximate each other as to their contents. For in the Quaestiones et solutiones also, the deeper allegorical significance is given as well as the literal meaning. In the great allegorical commentary on the contrary, the allegorical interpretation exclusively prevails. The deeper allegorical sense of the sacred letter is settled in extensive and prolix discussion, which by reason of the copious adducting of parallel passages often seems to wander from the text. Thus the entire exegetic method, with its draggin in of the most heterogeneous passages in elucidation of the idea supposed to exist in the text, forcibly recalls the method of Rabbinical Midrash. This allegorical interpretation however has with all its arbitrariness, its rules and laws, the allegorical meaning as once settled for certain persons, objects and events being afterwards adhered to with tolerable consistency. Especially is it a fundamental thought, from which the exposition is everywhere deduced, that the history of mankind as related in Genesis is in reality nothing else than a system of psychology and ethic. The different individuals, who here make their appearance, denote the different states of soul (τροποι της ψυχης) which occur among men. To analyse these in their variety and their relations both to each other and to the Deity and the world of sense, and thence to deduce moral doctrines, is the special aim of this great allegorical commentary. Thus we perceive at the same time, that Philo’s chief interest is not—as might from the whole plan of his system be supposed—speculative theology for its own sake, but on the contrary psychology and ethic. To judge from his ultimate purpose he is not a speculative theologian, but a psychologist and moralist (comp. note 183).

The commentary at first follows the text of Genesis verse by verse. Afterwards single sections are selected, and some of them so fully treated, as to grow into regular monographs. Thus e.g. Philo takes occasion from the history of Noah to write two books on drunkenness (περι μεθης), which he does with such thoroughness, that a collection of the opinions of other philosophers on this subject filled the first of these lost books (Mangey, i. 357).

The work, as we have it, begins at Gen. ii. 1; Και ετελεσθησαν οι ουρανοι και η γη. The creation of the world is therefore not treated of. For the composition, De opificio mundi, which precedes it in our editions, is a work of an entirely different character, being no allegorical commentary on the history of the creation, but a statement of that history itself. Nor does the first book of the Legum allegoriae by any means join on to the work De opificio mundi; for the former begins at Gen. ii. 1, while in De opif. mundi, the creation of man also, according to Gen. ii, is already dealt with. Hence—as Gfrörer rightly asserts in answer to Dähne—the allegorical commentary cannot be combined with De opif. mundi as though the two were but parts of the same work. At most may the question be raised, whether Philo did not also write an allegorical commentary on Gen. i. This is however improbable. For the allegorical commentary proposes to treat of the history of mankind, and this does not begin till Gen. ii. 1. Nor need the abrupt commencement of Leg. alleg. i seem strange, since this manner of starting at once with the text to be expounded, quite corresponds with the method of Rabbinical Midrash. The later books too of Philo’s own commentary begin in fact in the same abrupt manner. In our manuscripts and editions only the first books bear the title belonging to the whole work, Νομων ιερων αλληγοριαι. All the later books have special titles, a circumstance which gives the appearance of their being independent works. In truth however all that is contained in Mangey’s first vol.—viz. the works which here follow—belongs to the book in question (with the sole exception of De opificio mundi).

Emil Schürer comments:
“Περι μεθης. De ebrietate (Mangey, i. 357-391). On Gen. ix. 21. From the beginning of this book it is evident that another book preceded it, in which τα τοις αλλοις φιλοσοφοις ειρημενα περι μεθης were stated. This first book is lost, but it was still extant in the time of Eusebius, Euseb. H.E. ii. 18. 2: περι μεθης τοσαυτα (viz. two). Hieronymus, vir. illustr. 11: de ebrietate duo. They seem to have been in the hands of Johannes Monachus ineditus in the reverse order. For what he quotes with the formula εκ του περι μεθης α, is found in that which has come down to us; while what he cites with the formula εκ του περι μεθης δευτερου λογου, is not found in it (Mangey, i. 357, note).” (The Literature of the Jewish People in the Time of Jesus, p. 335)

J. H. A. Hart writes (The Jewish Quarterly Review Original Series 17, pp. 111-116):

In the de Plantatione Philo gives, so far as possible, the sayings of the other philosophers concerning intoxication, and now turns to consider the opinion of Moses. In the Law some are commanded to drink, others forbidden (e.g. the priests, Lev. x. 9); others again sometimes forbidden and sometimes commanded (Num. vi. 2 ff.). Moses, in fact, takes a more serious view of wine than the philosophers: to him it is the symbol of insensibility (αναισθησια) and lack of education (απαιδευσια), which produce the same disastrous results. This symbolism is clear in Deut. xxi. 18-21, where four charges are brought against the sinner:—disobedience, provocation, contribution to feasts, and intoxication. The first is, so to speak, the passive form of the second: the third, though praiseworthy if directed to a good object, is vitiated by folly: the fourth is the inflammation of boorishness or lack of education which ever burns the soul. The punishment pronounced upon the offender is that he should be expelled from yourselves (Deut. xxi. 21), for these guilty thoughts are within us. “Father” and “mother” may be explained either as the Creator and his Understanding (Prov. viii. 22), whose only and beloved son is the universe, or—better here—of right reason and general education.

Having thus reached an interpretation of the parents in question, Philo proceeds to discuss the four classes of their children: those who obey both or neither, and those who obey father or mother. Of the last class the plainest type is Jethro, “creation of confusion” (πλασμα τυφου), who will go only to his own land of false doctrine and unbelief (Ex. xviii. 16; Num. x. 29 f.), and convicts himself of impiety even in his pious professions (Ex. xviii. 11), by comparing God with false gods. Laban is such another, who substitutes human laws for the laws of nature when he refuses to give his younger daughter first in marriage (Gen. xxix. 26). But the athlete of wisdom (ο σοφιας ασκητης) knows that natures are independent of time; and, to take the passage in its ethical sense, all such must first consort with the younger education, that they may hereafter attain to an undisturbed enjoyment of the more perfect and mature. Yet how amazing it is that we cannot rise out of the clutch of phenomenal good things! Once there come any hope, however faint, of wealth or fame, we yield and cannot resist. Womanish custom (for Rachel speaks “of the custom of women,” Gen. xxxi. 35) prevails, and we cannot wash it out and run to the home of men, like Sarah (Gen. xviii. 14) when she was about to bear Isaac, the self-taught; for to men belongs the following of nature instead of custom. But though we are still the prey of our senses and passions, we shall have an ally, none the less, in our mother, middle education, who records what is considered just in every city, and lays down the law thus for this people and thus for that.

Some there are who can obey the behests of their father, and their reward is the priesthood. “And if we narrate the course of action in which they won this privilege we shall be mocked, perhaps, by many who are deceived by superficial appearances and do not descry the unseen and overshadowed powers.” These priests were murderers, fratricides (Exod. xxxii. 27 ff.). Yes, but Scripture does not say murderers of men. Their victims are the affections of the flesh, the band of the senses and speech (ο κατα προφοραν λογος), which is nearest of all to the mind. Such are they who honour their father and all that is his, but think little of their mother and all that is hers.

Those who are at war with both parents are like him who said, “I know not the Lord, and Israel I send not away” (Exod. v. 2). They are not yet extinct but exist to plague mankind, impious as regards God, untrustworthy as regards their fellows.

Those who obey both are good keepers of the laws which their father, right reason, laid down, and faithful stewards of the customs which education, their mother, introduced. They were taught by the one to honour the Father of the universe, and by the other not to despise that which is universally considered justice (θεσει not φυσει). And so Jacob becomes Israel. The learner attains perfection, complete insight and wisdom. And as the art of Pheidias is stamped unmistakably on all his works, whatever the material—brass, ivory, gold, what not—so the true form (ειδος) of wisdom, the art of arts, remains unchangeable on whatever material it be impressed.

So much, then, for the children of this pair. Rightly is the disobedient, provocative, prodigal drunkard expelled as a worshipper of the golden calf (Exod. xxxii. 17-19). Scripture allegorizes bodily life and calls it the camp wherein is war. Far off will the wise man pitch his tent, removing to the divine peaceful life of rational and happy souls (Exod. xxxiii. 7).

“When I go forth from the city, then will I stretch out my hands unto the Lord, and the voices shall cease” (Exod. ix. 29). No man said that, but the mind which, contained in the city of the body and mortal life, is cribbed, cabined and confined as in a prison. With Abraham (Gen. xiv. 22 f.), he that has seen the Absolute recognizes no secondary cause. All good things come from God, not from the immediate sources through which we derive them. The voice of war is the voice of men who make a beginning of wine (φωνην εξαρχοντων οινου); those who wilfully take the way that leads to lack of education and folly. Pray then that this may never happen to thee, and so, when thy prayers are fulfilled, thou shalt be no longer a layman (ιδιωτης) but a priest.

For only to priests and worshippers of God belong sober sacrifices (Lev. x. 8-10). Aaron, “the mountainous,” is the reason that minds high and lofty things and renounces wine and every drug of folly, including wine. The literal sense of the passage is wonderful enough: it is only reverent that one should come to prayers and sacrifices sober and self-possessed. If, however, we suppose that neither the tabernacle nor the altar is the visible thing fashioned out of lifeless and corruptible matter, but the unseen, intellectual object of speculation (θεωρημα), of which this is the perceptible image, then he will marvel the more at the command. The tabernacle is the symbol of bodiless virtue, the altar that of an image perceptible though it never be perceived, just as a log sunk in mid-Atlantic is never burned, though meant for burning. The form of words and expression shows that the writer is not conveying a command merely, but setting forth a meaning (γνωμην αποφαινομενος). For he says, “ye shall not drink,” and such an one “will not die.” It is an eternal ordinance that education is a healthful and a saving thing, and the lack of it the cause of disease and death.

Similarly, Samuel will never drink wine or strong drink (1 Kings i. 11), for he has been ranked—as his name denotes—in the ranks of the divine camp. Perhaps he lived as a man, but he has been conceived of not as a composite living thing of flesh and blood, but as a mind rejoicing only in the service and worship of God. His mother Hannah was accused of drunkenness (1 Kings i. 14), for in those inspired by God (τοις θεοφορητοις) not only is the soul raised but the body is flushed and inflamed by inward joy. Great is the boldness of the soul that is filled with the graces of God. This then is the band (χορος) of the sober, who make education their leader; the other that of drunkards, whose leader (εξαρχος) is boorishness (απαιδευσια).

The other sense which “wine” bears in Scripture is insensibility or ignorance, the insensibility of the soul, the opposite of which is skill or knowledge (επιστημη), which is, so to speak, the soul’s eyes and ears. There are two kinds of ignorance, the one simple, i. e. complete insensibility, the other double when one is not only possessed by lack of knowledge but imagines he knows what he does not know, being uplifted by a false opinion of wisdom. Of these the second is the greater evil, as it produces wilful wrongdoing. So Lot has two daughters, Counsel and Consent, by his wife Convention, who was turned to stone (λιθουμενης); and they lead him completely astray. But as a matter of fact the senses are not sure guides. Many of the objects of sense are continuously varying. Among animals the chameleon and the polypus change colour with their environment; the dove’s neck changes its hues in the sun’s rays; and the reindeer is hard to hunt, not so much on account of its strength as because it adopts a protective colouring suited to any surroundings. The same variation is found among men. Often at a theatre I have seen some of the audience so carried away by the performance as to rise involuntarily and applaud, others as unmoved as the benches on which they sit, and others so alienated as to get up and go, hands over ears.

The refraction of water and the deceptiveness of a distant view all point in the same direction. Indeed we can never perceive any sensible object as it is, but always in relation to something else. Nothing at all in the world is known save by comparison with its opposite. All sense-perception is a complex process and therefore uncertain, and even judgments of right and wrong depend upon early education in the case of most men. The multitude believes what was once delivered to it, and, having left its mind untrained, affirms and denies without independent examination. The philosophers, on the other hand, who test and examine all questions, logical, ethical and physical, cannot agree in their answers. So reserve of judgment is the safest course.

F. H. Colson and G. H. Whitaker write:
“This treatise like its two predecessors is founded on Gen. ix. 20-29, particularly the last words, ‘And (Noah) drank of the wine and was drunken.’ Philo, however, from the first breaks away from this text and, having discussed at the end of the De Plantatione the various philosophical views on drunkenness, proceeds to consider the views of Moses on the subject. He lays down that Moses uses wine as a symbol for five things: (1) foolishness or foolish talking; (2) complete ‘insensibility’; (3) greediness; (4) cheerfulness and gladness; (5) nakedness (1-5). He then gives a short introductory explanation of each of these, dwelling particularly on one aspect of “nakedness” as the truth which strips off all disguises from virtue and vice, and this leads to a short digression on the mutually exclusive nature of these two (6-10), a thought evidently suggested by Socrates’ fable of Pleasure and Pain in the Phaedo. He then proceeds to a detailed consideration of these five, though as a matter of fact only the first three are treated in what has come down to us.” (Philo, vol. 3, pp. 308-309)