415. And I looked, and I heard an angel flying in the midst of heaven. (8:13) This symbolizes instruction and prediction from the Lord.

In the highest sense an angel means the Lord, and so also something from the Lord (no. 344). And to fly in the midst of heaven and speak means, symbolically, to perceive and understand, and when said of the Lord, to foresee and provide (no. 245). But here it means to instruct and predict.

Being "filled" means being endowed with a spiritual quality. When the material in question is good -- water, food, people who represent good things, etc. -- it means getting a desire for good and an understanding of truth from the Lord. When the material is bad -- dust, flies, emotions like despair or terror, etc. -- it means being overwhelmed and enslaved by the desire for evil and the false, twisted logic that supports it. There are a number of references in the Bible to "filling the hand," which has a specific meaning and is dealt with separately.