Full Idea
The supreme happiness of man consists in the greatest possible increase of his perfection.
Gist of Idea
Supreme human happiness is the greatest possible increase of his perfection
Source
Gottfried Leibniz (Of Organum or Ars Magna of Thinking [1679], p.1)
Book Reference
Leibniz,Gottfried: 'Philosophical Writings', ed/tr. Parkinson,G.H.R. [Dent 1973], p.1
A Reaction
I fear that (being a great intellectual) he had a rather intellectual interpretation of 'perfection'. This is in danger of being a tautology, but if the proposal is given an Aritotelian slant I am sympathetic.