By application of course it told those who first read it of the cause of all declension - failure to hear what the Spirit had already said to the Churches by the Apostle Paul. By application also, it reminds us of the same cause today. But the interpretation which will exhaust the seven-fold expression is that which leaps over the present Church period, and links together the Gospels and Acts with the Apocalypse.
The expression (which is slightly varied in form) as first used in the Gospels is connected solely with, and marks, a change of dispensation. When used again in Revelation another great change of dispensation is about to take place. It is to be wrought by "the Son of Man," who has received authority to show it to "His servants."
Such a change could be known only to God, ruled and over-ruled by Him. None but Divine foreknowledge, therefore, could make it known.
The Son of Man alone made use of this weighty expression: and on fourteen separate occasions He called for the deepest attention to what was being announced.
Now, the number fourteen is most significant; twice seven, denoting a special Divine revelation made by "the Son of Man."
And these fourteen  are divided into six and eight (just as seven is divided into three and four). For six of them occur in the Gospels and eight in the Revelation. Six were spoken by Him as the Son of Man on earth, and eight as the Son of Man from glory. Six being the number pertaining to man, and eight being the number connected with resurrection. 
The six occasions on earth are Matt. xi.15; xiii.9,43. Mark iv.23: vii.16, and Luke xiv.35.
The eight from Heaven are Rev. ii.7,11,17,29; iii.6,13,22; and xiii.9.
These, like the six in the Gospels, are Dispensational, and are thus associated with the great change in God's relation to the earth, to "the Jew and the Gentile," which was about to take place.
The first use of the expression in Matt. xi.15 is most significant, and stamps it as belonging to the setting up of the kingdom with power and glory. Elijah's presence on the holy mount characterises the scene there as representing the power and coming of that kingdom (Matt. xvi.28.2 Pet. i.16,17,18), while Mal. iv.5 (Heb. iii.23) connects Elijah's ministry with the setting up of that kingdom.
It has been proclaimed of John before his birth "he shall go before Him (i.e, Messiah) in the spirit and power of Elijah" (Luke i.17); and again, in Luke i.76,77, it was announced: "And thou, child, shalt be called prophet of the Highest  : for thou shalt go before the face of the Lord to prepare his ways; to give knowledge of salvation unto his people, by (marg., for) the remission of their sins," etc.
John the Baptist was therefore invested with Elijah's "spirit and power" (i.e., Elijah's spiritual power), and was specially designated as "the prophet of the Most High."
Therefore our Lord could say in Matt. xi.14,15: "If ye will receive him, this is (i.e., represents) Elijah which was for to come. He that hath ears to hear, let him hear."
But "their ears were dull of hearing" (Matt. xiii.15), fulfilling the dispensational prophecy of Isa. vi.10: Therefore they did not "receive him;" and, consequently, "Elijah the prophet" is still to come. Hence it is that, in the Book which relates to the events connected with the ministry of Elijah and his work in connection with the restoration of the kingdom, we again meet with this dispensational admonition: which takes us back not merely to Matt. xi.15, but to Ma. iv.5, "He that hath ears to hear, let him hear."
Thus we have in the expression another proof that the Church of God is not the subject of the Apocalypse; and that we are reading here, not of the period belonging to the ministry of Paul the Apostle, or of the period of present Church history, as the historicists assert; but, of that which belong to the ministry of "Elijah the Prophet."
 The occasions were 14, but the actual occurrences of this example of the Figure are sixteen on account of the repetition of the Parable of the Sower in the parallel Gospel records. Sixteen is a square number (4X4) marking completeness.  For the significance of these numbers see Number in Scripture.  This title is always connected with dominion in the earth. See Genesis 14:18-22.
 For the significance of these numbers see Number in Scripture.
 This title is always connected with dominion in the earth. See Genesis 14:18-22.