Full Idea
The only form of servitude which has no dishonour has for its object the acquisition of excellence.
Clarification
'Excellence' here is the Greek word 'areté', which also translates as 'virtue'
Gist of Idea
The only slavery which is not dishonourable is slavery to excellence
Source
Plato (The Symposium [c.373 BCE], 184c)
Book Reference
Plato: 'The Symposium', ed/tr. Hamilton,W [Penguin 1951], p.51