A dictionary of Proverbs (Oxford Paperback Reference)

belly see what is GOT over the Devil’s back is spent under his belly.
bent see as the TWIG is bent, so is the tree inclined.
All’s for the BEST in the best of all possible worlds
This saying translates Voltaire’s Tout est pour le mieux dans le meilleur des mondes possibles, the observation which the philosophical optimist Dr Pangloss in Candide (1759) persists in making, despite overwhelming evidence to the contrary.

• 
  1911 G. B. SHAW Shewing-up of Blanco Posnet 299 The administrative departments were consuming miles of red tape in the correctest forms of activity, and everything was for the best in the best of all possible worlds. 1943 A. CHRISTIE Moving Finger XV. I agreed with happy Miss Emily that everything was for the best in the best of possible worlds. 1961 WODEHOUSE Ice in Bedroom ii. Fate had handed him the most stupendous bit of goose [luck] and.. all was for the best in this best of all possible worlds. "content and discontent; optimism
  

The BEST is the enemy of the good
Also the GOOD is the enemy of the best. Cf. 1770 VOLTAIRE Questions sur L’Encyclopedie II. 250 c’est bien ici qu’on peut dire Il meglio e I’inimico del bene, and 1772 La Beguele in (Luvres Competes (1877) X. 50 le mieux est l’ennemi du bien.

• 
  1861 R. C. TRENCH Commentary on Epistles to Seven Churches in Asia p. v. ‘The best is oftentimes the enemy of the good’; and.. many a good book has remained unwritten .. because there floated before the mind’s eye.. the ideal of a better or a best. 1925 Times 1 Dec. 16 This is not the first time in the history of the world when the best has been the enemy of the good;.. one single step on.. solid ground may be more profitable than a more ambitious flight. 1960 D. JONES Letter 1 June in R. Hague Dai Greatcoat (1980) III. 182 Tom told me a very good Spanish proverb: ‘The best is the enemy of the good.’ 1981 Times 2 Mar. 13 To maintain that all that a school provides must be provided free makes the best the enemy of the good. "good things