there is a middle ground in things, there is a middle way; from Horace's Satires 1.1.106; see also: Golden mean (philosophy). According to Potempski & Galmarini (Atmos. Chem. Phys., 9, 9471–9489, 2009) the sentence should be translated as: "There is an optimal condition in all things" which in the original text is followed by the sentence: "There are therefore precise boundaries beyond which one cannot find the right thing" (sunt certi denique fines quos ultra citraque nequit consistere rectum).
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