Fiery spirits and airy celestial globes

Meaning

I.8.1 says celestial spirits are made from pure fiery substance, whereas celestial globes and their lights are composed of the intermediate airy substance. It distinguishes two origins or constitutions, not merely spirits from the instruments of their activity. The general celestial nature is not presented as a uniform mass with no internal degrees. The passage's language of temper or temperature concerns a balanced constitution, not a numerical heat reading.

The distinction supports the broader argument that one genus can appear differently in its species. A product can possess the perfection appropriate to simple Nature while lacking the intensified perfection later claimed for art. Celestial vocabulary therefore supplies a model of differentiated reception and balance, not an instruction to identify all heavenly bodies with one material fire or a modern astronomical substance.