“I can be a good friend, or a bad enemy.”

Journal to Stella (30 June, 1711)

Source: One Minute Nonsense (1992), p. 152
Context: "What can I do to see Reality as it is?"
The master smiled and said, "I have good news and bad news for you, my friend."
"What's the bad news?"
"There's nothing you can do to see — it is a gift."
"And what's the good news?"
"There's nothing you can do to see — it is a gift."

The Son of Neptune

http://www.telegraph.co.uk/sport/main.jhtml;jsessionid=CEDUJVE3P05PLQFIQMFSFFOAVCBQ0IV0?xml=/sport/2002/05/01/sotys02.xml&page=2
On himself

Thoughts upon Hare and Fox Hunting (1781), Letter 3

Garantissez-moi de mes amis, écrivait Gourville proscrit et fugitif, je saurai me défendre de mes ennemis. ("Defend me from my friends," wrote Gourville, exile and fugitive, "I can defend myself from my enemies.") — Gabriel Sénac de Meilhan, Considérations sur l'esprit et les moeurs (1788): "De L'Amitié." Sénac de Meilhan was quoting Jean Hérault, sieur de Gourville (1625 - 1703).
The remark has often been attributed to Voltaire and to Claude-Louis-Hector de Villars.
Misattributed

Variation: Defend me from my friends; I can take care of my enemies myself The quote has been attributed to Voltaire, who was using it after Villars. Quoted in Connie Robertson, Dictionary of Quotations, 1998
Source: The 48 Laws of Power

In response to George Henry Lewes (LL, II, v, 272); Miriam Farris Allott (1974), The Brontës, the critical heritage, page 160;