65 According to L&N 23.184 this could be mainly a psychological experience rather than actual loss of consciousness. It could also refer to complete discouragement because of fear, leading people to give up hope (L&N 25.293).
66 An allusion to Isa 34:4. The heavens were seen as the abode of heavenly forces, so their shaking indicates distress in the spiritual realm. Although some take the powers as a reference to bodies in the heavens (like stars and planets, “the heavenly bodies,” ) this is not as likely.

In other versions

people fainting with fear and with foreboding of what is coming on the world. For the powers of the heavens will be shaken.

People will faint from terror, apprehensive of what is coming on the world, for the heavenly bodies will be shaken.

People will faint from fear and expectation of the things that are coming on the world, because the powers of the heavens will be shaken.

People will be terrified at what they see coming upon the earth, for the powers in the heavens will be shaken.

people fainting from fear and expectation of what is coming on the inhabited earth, for the powers of the heavens will be shaken.

Men’s hearts failing them for fear, and for looking after those things which are coming on the earth: for the powers of heaven shall be shaken.

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