Daniel 8:26-27 (YLT)
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And the appearance of the evening and of the morning, that is told, is true; and thou, hide thou the vision, for it is after many days.'
And I, Daniel, have been, yea, I became sick for days, and I rise, and do the king's work, and am astonished at the appearance, and there is none understanding.
Daniel 12:8-9
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And I have heard, and I do not understand, and I say, 'O my lord, what is the latter end of these?'
And he saith, 'Go, Daniel; for hidden and sealed are the things till the time of the end;
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Isaiah 29:10
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For poured out on you hath Jehovah a spirit of deep sleep, And He closeth your eyes -- the prophets, And your heads -- the seers -- He covered.
And the vision of the whole is to you, As words of the sealed book, That they give unto one knowing books, Saying, 'Read this, we pray thee,' And he hath said, 'I am not able, for it is sealed;'
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Revelation 5:1
And I saw upon the right hand of Him who is sitting upon the throne a scroll, written within and on the back, sealed with seven seals;
and I saw a strong messenger crying with a great voice, 'Who is worthy to open the scroll and to loose the seals of it?'
and no one was able in the heaven, nor upon the earth, nor under the earth, to open the scroll, nor to behold it.
And I was weeping much, because no one was found worthy to open and to read the scroll, nor to behold it,
and one of the elders saith to me, 'Weep not; lo, overcome did the Lion, who is of the tribe of Judah, the root of David, to open the scroll, and to loose the seven seals of it;
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A safe principle is to let the bible interpret itself.