Full Idea
The differentia of the good life …is controlled by the consciousness of there being some perfection which has to be fulfilled, some law which has to be obeyed, something absolutely desirable whatever the individual may for the time desire.
Gist of Idea
The good life aims at perfections, or absolute laws, or what is absolutely desirable
Source
T.H. Green (Prolegomena to Ethics [1882], p.134), quoted by John H. Muirhead - The Service of the State II
Book Reference
Muirhead,John H.: 'The Service of the State: T.H. Green' [John Murray 2021], p.29
A Reaction
The 'perfection' suggests Plato, and the 'law' suggests Kant. The idea that something is 'absolutely desirable' is, I suspect, aimed at the utilitarians, who don't care what is desired. I'm no idealist, but have some sympathy with this idea.