Fear not, as in Genesis 20:8, signifies aversion. To fear signifies to disbelieve or not to have faith and love, as in Isaiah 43:1, 5; 44:8; Mark 5:36; Luke 1:73, 75; 4:40; 8:49; 12:7, 32.

Fear not, as in Revelation 1:17; Daniel 10:5, 12; Matthew 17:5, 7; 28:10, etc., signifies resuscitation to life, and at the same time adoration from the most profound humiliation.

(Notae: Apocalypse Revealed 56)

511. And great fear fell on those who saw them. This symbolizes a disturbance of the mind and alarm at Divine truths.

The symbolic meaning of fear varies, depending on what it affects. Here it symbolizes a disturbance of the mind and alarm at Divine truths, as Divine truths have this effect on evil people. For evil people are terrified as soon as they hear about hell and eternal damnation. But the terror soon dissipates, along with their belief in the existence of any life after death.