Revelation chapter 6:
"I watched as the Lamb opened the first of the seven seals. Then I heard one of the four living creatures say in a voice like thunder, 'Come!'"
...
"I watched as he opened the sixth seal. There was a great earthquake. The sun turned black like sackcloth made of goat hair, the whole moon turned blood red, and the stars in the sky fell to earth, as figs drop from a fig tree when shaken by a strong wind. The heavens receded like a scroll being rolled up, and every mountain and island was removed from its place."
What is a seal? A document sealed is one that cannot open until the breaking of the seal. The things sealed are things NOT allowed to happen in any circumstance until an appointed time. Only one person could open that Rev set of seals so nobody else could bring about those kinds of events spoken of in the sealed document, and the one worthy only opens it in God's time. So the events can never be allowed to happen until the seal is broken. There is a saying "So and so will stop at nothing if ..." but God does not behave as one who will stop at nothing - He stops from allowing the kinds of events like the Revelation 6 sixth seal but eventually even those events will be allowed. I think soon this sixth seal will be broken by Lord Jesus if it hasn't be broken by Him already. This does not mean immediately the apocalyptic events will happen, in my understanding, but that once that seal is broken they are no longer ruled out - and eventually (Revelation chapter 16 shows) they will happen.
So once that sixth seal is broken by Jesus Christ a whole load of things are suddenly on that table that were kept off it before.
