1. The four elements and the two lifeforms.
....(earth, water, air, fire,/plants and animals/man
2. The 7 churches of Revelation
3. The 7 seals
4. The 7 trumpets
5. The 7 vials
6. The 7 millenniums of our history
7. The 7 stages of our growth(and a plant's growth)
When the angels cast their vials upon first the "earth", then the "sea"(water), and then the rivers(which are surrounded by the growth of plants, grass, trees ect). Then the 4th angel casts his vial upon the "fires" of lights. These four elements were much discussed and published by Aristotle. The only thing is, he must not have read Genesis. Because he listed them irrationally as "earth, water, fire, air) Well, I guesse he was preChristian. He never had the light.