"Having reached this point, we must defend our childhood. And we have still to explain what is said by the apostle: 'I have fed you with milk (as children in Christ), not with meat; for ye were not able, neither yet are ye now able.' For it does not appear to me that the expression is to be taken in a Jewish sense; for I shall oppose to it also that Scripture, 'I will bring you into that good land which flows with milk and honey.' A very great difficulty arises in reference to the comparison of these Scriptures, when we consider." (Clement of Alexandria, The Instructor, Book 1, Chapter 6)Clement continues his defense for our continued childhood in God and our continued need for an Instructor. Here he is taking up the words of the apostle and the words of the scripture; one seeming to indicate that milk is only for the young and the other indicating that milk was to be part of our rest in the promise land, a rest that accompanies arrival, perfection, and maturity.
"For if the infancy which is characterized by the milk is the beginning of faith in Christ, then it is disparaged as childish and imperfect. How is the rest that comes after the meat, the rest of the man who is perfect and endowed with knowledge, again distinguished by infant milk? Does not this, as explaining a parable, mean something like this, and is not the expression to be read somewhat to the following effect: 'I have fed you with milk in Christ;' and after a slight stop, let us add, 'as children,' that by separating the words in reading we may make out some such sense as this: I have instructed you in Christ with simple, true, and natural nourishment,—namely, that which is spiritual: for such is the nourishing substance of milk swelling out from breasts of love." (Clement of Alexandria, The Instructor, Book 1, Chapter 6)Clement's contention is that milk, while appropriate for children, is is also useful for adults; milk simply referring to that which is simple, pure, and spiritual not that which is only for infants. While we grow up on the "pure milk of the word" (1 Peter 2:2) we never grow out of our need of it or for its regenerative properties in our lives. Even as adults, we all need milk along with meat. Thus milk to to be part of our diet no matter how long we walk with the Lord.
"Thus, then, the milk which is perfect is perfect nourishment, and brings to that consummation which cannot cease. Wherefore also the same milk and honey were promised in the rest. Rightly, therefore, the Lord again promises milk to the righteous, that the Word may be clearly shown to be both, 'the Alpha and Omega, beginning and end;' the Word being figuratively represented as milk." (Clement of Alexandria, The Instructor, Book 1, Chapter 6)However, Paul's words to the Corinthians that they could not eat meat but only drink milk was not because they remained children and had not grown into manhood but was because they were still acting carnal and not spiritual.
"so that the carnal may be understood as those recently instructed, and still babes in Christ. For he called those who had already believed on the Holy Spirit spiritual, and those newly instructed and not yet purified carnal; whom with justice he calls still carnal, as minding equally with the heathen the things of the flesh" (Clement of Alexandria, The Instructor, Book 1, Chapter 6)Clement also reminds us that Paul says that he gave them milk to "drink" while infants "suck." Here obviously not separating milk for infants and meat for grownups.
"In saying, therefore, 'I have given you milk to drink,' has he not indicated the knowledge of the truth, the perfect gladness in the Word, who is the milk? And what follows next, 'not meat, for ye were not able,' may indicate the clear revelation in the future world, like food, face to face. “For now we see as through a glass,” the same apostle says, 'but then face to face.' Wherefore also he has added, 'neither yet are ye now able, for ye are still carnal,' minding the things of the flesh,—desiring, loving, feeling jealousy, wrath, envy." (Clement of Alexandria, The Instructor, Book 1, Chapter 6)So what distinguishes milk from meat? Clement believes that the milk and the meat of the Word do not differ in substance, but in their administration and application to our life.
"regarding the meat not as something different from the milk, but the same in substance. For the very same Word is fluid and mild as milk, or solid and compact as meat. And entertaining this view, we may regard the proclamation of the Gospel, which is universally diffused, as milk; and as meat, faith, which from instruction is compacted into a foundation, which, being more substantial than hearing, is likened to meat, and assimilates to the soul itself nourishment of this kind." (Clement of Alexandria, The Instructor, Book 1, Chapter 6)Both milk and meat represent the Word of God and both are valuable in our lives. It is the milk that grows us up in Christ and the meat, along with the milk, that sustains us in our walk with the Lord. Milk is applicable for everyone, but as we learn to discern the Lord's voice and discipline our lives in obedience to that "milk", we grow in our ability to eat and assimilate meat. Milk is for everyone, but meat is only beneficial to the trained.