Proclus: Commentary on the Timaeus of Plato

"That the design of the Platonic Timaeus embraces the whole of physiology and that it pertains to the theory of the universe, discussing this from the beginning to the end, appears to me to be clearly evident to those who are not entirely illiterate." -- Proclus, philosopher, 5th century

"Hence the fire which is there (in the heavenly bodies) is light; and it is not proper to disturb the discussion of it, by directing our attention to the gross and dark fire of the sublunary region." -- Proclus, philosopher, 5th century

"It is also evident that the middle elements should be in the heavenly bodies, but that different elements should abound in different parts of the celestial regions." -- Proclus, philosopher, 5th century