We have clues related to Philip 2's wife and the person Proust was arguing with.
Added 4 minutes later
Regarding Proust: I believe he's referring to Joseph Louis, and he was arguing with (from Wikipedia):
Proust's opponent in the ensuing debate about the constancy of the composition of chemical compounds was his compatriot, the famous chemist Claude Louis Berthollet. The polemic between these two scientists lasted from 1801 to 1808.
Profanum vulgus et inscium ne attrectato:
Omnesque Astrologi Blenni, Barbari procul sunto
Qui aliter facit, is rite sacer esto