The commentators are much divided and exercised on the question whether the Apostle means that the argument should advance or that his readers ought to make progress in spiritual character.[84] In a way he surely means both. What gives point to the whole section now to be considered is the connection between development of doctrine and a corresponding development of the moral nature. “For the time ye ought to be teachers.”[85] They ought to have been teachers of the elementary truths, in consequence of having discovered the higher truths for themselves, under the guidance of God’s Spirit. It ought to have been unnecessary for the Apostle to explain them. At this time the “teachers” in the Church had probably consolidated into a class formally set apart, but had not yet fallen to the second place, as compared with the “prophets,” which they occupy in the “Teaching of the Twelve Apostles.” A long time had elapsed since the Church of Jerusalem, with the Apostles and elders, had sat in judgment on the question submitted to their decision by such men as Peter, Barnabas, Paul, and James.[86] Since then the Hebrew Christians had degenerated, and now needed somebody—it mattered little who it might be,[87]—to teach them the alphabet[88] of Christian doctrine. Philo had already emphasised the distinction between the child in knowledge and the man of full age and mature judgment. St. Paul had said more than once that such a distinction holds among Christians. Many are carnal; some are spiritual. In his writings the difference is not an external one, nor is the line between the two classes broad and clear. The one shades into the other. But, though we may not be able to determine where the one begins and the other ends, both are tendencies, and move in opposite directions. In the Epistle to the Hebrews the distinction resembles the old doctrine of habit taught by Aristotle. Our organs of sense are trained by use to distinguish forms and colours. In like manner, there are inner organs of the spirit,[89] which distinguish good from evil, not by mathematical demonstration, but by long-continued exercise[90] in hating evil and in loving holiness. The growth of this spiritual sense is connected by our author with the power to understand the higher doctrine. He only who discerns, by force of spirited insight, what is good and what is evil, can also understand spiritual truths. The difference between good and evil is not identical with “the word of righteousness.” But the moral elevation of character that clearly discerns the former is the condition of understanding also the latter.