Fond man! though all the heroes of your line Bedeck your halls, and round your galleries shine In proud display; yet take this truth from me— Virtue alone is true nobility!
Juvenal, Satire VIII, line 29. Gifford's translation. "Virtus sola nobilitat," is the Latin of last line.
Noblesse oblige.
There are obligations to nobility.
Comte de Laborde, in a notice to the French Historical Society in 1865, attributes the phrase to Duc de Levis, who used it in 1808, apropos of the establishment of the nobility.
This was the noblest Roman of them all: All the conspirators save only he Did that they did in envy of great Cæsar; He only, in a general honest thought And common good to all, made one of them.