Full Idea
Do not say or do what is base, even when you are alone. Learn to feel shame in your own eyes much more than before others.
Gist of Idea
Behave well when alone, and feel shame in you own eyes
Source
Democritus (attrib) (reports [c.250 BCE], B244), quoted by John Stobaeus - Anthology 3.31.7
Book Reference
'Ancilla to the Pre-Socratic Philosophers', ed/tr. Freeman,Kathleen [Harvard 1957], p.113
A Reaction
I like this. How you think and behave when unobserved is the true test of who you are. Feeling shame at a very private failing is an interesting phenomenon.