The Roman History · Amm. 20.11.29

Others think that the rainbow is caused by the rays of the sun becoming infused into some dense cloud, and pouring into it a liquid light, which, as it can find no exit, falls back upon itself, and shines the more brilliantly because of a kind of attrition; and receives those hues which are most akin to white from the sun above; its green hues from the cloud under which it lies, as often happens in the sea, where the waters which beat upon the shore are white, and those farther from the land, which, as being so, are more free from any admixture, are blue.

Ammianus Marcellinus · translated by C. D. Yonge · 1911 reprint
C. D. Yonge translation (preface dated February 1862); G. Bell and Sons, 1911; Project Gutenberg #28587
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