The Greek Inscription on Henry Neville's Portrait: Solved!

Before leaving for France as ambassador in early 1599, Henry Neville had his portrait painted by Marcus Gheeraerts the Younger:

The top left of the portrait has astronomical symbols and some Greek writing:

An anonymous scholar, expert in this field, has graciously provided an explanation of the symbol and the Greek text:

The Greek, "Absolutely without prosthaphaeresis"; the latter term is used here to mean the astronomical "correction" between mean and true position. And the diagram shows the sun at apogee and perigee, depicting accurately the alternative epicycle solar model of Ptolemy, at which points the true position of the sun (the picture of the sun) and the mean position of the sun (the center of the epicycle) coincide, as seen from the center or along the line of apsides (also shown in the diagram) -- so that there is no correction, or prosthaphaeresis. 

Neville is clearly using this astronomical fact as an emblem of his directness and trustworthiness -- that there is no "correction" needed between his apparent and true self. A clever conceit!

I believe Neville here is creating a clever version of his family motto: "ne vile velis". This Latin motto is usually translated as "do nothing base or dishonorable" or  "nothing distasteful or vulgar". This Greek text, along with the astronomical symbols, seem to imply something very similar.

During their tour of Europe, Henry Neville and his tutor Henry Savile met with Paul Wittich, one of the people who developed the mathematical technique of prosthaphaeresis. Tycho Brahe also made heavy use of this method; there is a great deal of scholarship connecting the Danish Brahe with certain aspects of Hamlet. The inscription, however, emphasizes the word as used in Ptolemaic astronomy, rather than the word's use to describe the mathematical method.