Valens' major work is the Anthology (Latin: Anthologia), ten volumes in Greek written roughly within the period 150 to 175.
A working professional astrologer, Valens includes over a hundred sample charts from his case files in the Anthology.
Although originally a native of Antioch, he appears to have travelled widely in Egypt in search of specific astrological doctrines to bolster his practice.
At the time Alexandria was still home to a number of astrologers of the older Babylonian, Greek and Egyptian traditions.
Modern scholars tend to counterpoise the two men, since both were roughly contemporary and lived in Alexandria; yet Valens' work elaborated the more practical techniques that arose from ancient tradition, while Ptolemy, very much the scientist, tended to focus more on creating a theoretically consistent model based on his Aristotelian causal framework.