Clement of Alexandria

So also may we take the Scripture: "And I, brethren, could not speak unto you as unto spiritual, but as unto carnal, even as unto babes in Christ;" 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: "For whereas there is among you envy and strife, are ye not carnal, and walk as men?" "Wherefore also I have given you milk to drink," he says; meaning, I have instilled into you the knowledge which, from instruction, nourishes up to life eternal.