stet sol

I know Sol is a god of sun. But stet sol, what's the meaning? Thanks.

[Mr Quantz] told me that His Majesty . . . played no other concertos than those which he [Quantz] had expressly composed for his use, which amounted to three hundred, and these he performed in rotation. This exclusive attachment to the productions of his old master may appear somewhat contracted, however, it implies a constancy of disposition but rarely to be found among princes. . . . It is an indication of a sound judgement and of great discernment, in His Majesty, to adhere thus firmly to the productions of a period which may be called the Augustan Age of music; to stem the torrent of caprice and fashion with such unshaken constancy is possessing a kind of stet sol by which Apollo and his sons are prevented from running riot or changing from good to bad and from bad to worse---TimeandPower

Maybe I should trpe God.

'Stet' is Latin for "let it stand" (and as such is used in proof-reading), so 'stet sol' would mean "may the sun stand still", and evidently refers to something in mythology which I can't identify. The king (Frederick the Great, I think?) is commanding the sun not to move, metaphorically speaking.

Stet sol is not in this list of Latin expressions commonly used in English.
As Entangledbank says, it means something like "Stop the sun!". Sol is both the sun and the sun-god. Apollo is a Roman god who was at certain times identified with Sol.
I am sure the Latin forum on WordReference will be glad to help further.