The original text reads:
Doge: It is consistency which forms and proves it:
Vice cannot fix, and Virtue cannot change.
The once fall'n woman must for ever fall;
For Vice must have variety, while virtue
Stands like the Sun, and all which rolls around
Drinks life and light from her aspect
( Marino Faliero, Act II, Scene 1, ll. 393-98, in Byron, The Poetical Works, p. 422)
By 1820 Byron had become deeply involved with the cause of Italian patriots. Marino Faliero is a poetic drama of a political conspiracy which revolves around the character of a famous if irascible old Doge of Venice who sacrifices his throne, his honour and his life to cleanse his country of corruption (see Ruskin and Byron).