“Briarwood is the pretty poison. There is no cure for Briarwood.”
“Poison cures in certain contingencies, and in those cases poison is not an evil thing.”
Le venin guerit en quelque rencontre, et, ce cas-là, le venin n'est pas mauvais.
Aristippe, ou De la cour (1658), Discours VI.
Translation reported in Harbottle's Dictionary of quotations French and Italian (1904), p. 139.
Original
Le venin guerit en quelque rencontre, et, ce cas-là, le venin n'est pas mauvais.
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Jean-Louis Guez de Balzac 8
French author, best known for his epistolary essays 1597–1654Related quotes
Source: Drenai series, The Swords of Night and Day, Ch. 21
Context: "No golden age to discover now," he whispered. "No end to disease and starvation. No, bright sparkling cities reaching the clouds... All that I have lived for is gone now. I am so tired.""Then think on this, priest: You stopped the Eternal from finding greater weapons. Your actions here have led to her death. The world is free again.""Free? Of one tyrant perhaps. You think there will be no others?""No, I do not. But I know there will always be men to stand against them. You grieve because of a pure magic lost. That magic was corrupted by evil. This is how evil thrives. We find an herb that cures disease, and someone will make a poison from it. We forge iron to make a better plow, and someone will make a sharper sword. There can be no power that evil will not corrupt."

“My master Attalus used to say: "Evil herself drinks the largest portion of her own poison." The poison which serpents carry for the destruction of others, and secrete without harm to themselves, is not like this poison; for this sort is ruinous to the possessor.”
Quemadmodum Attalus noster dicere solebat, 'malitia ipsa maximam partem veneni sui bibit'. Illud venenum quod serpentes in alienam perniciem proferunt, sine sua continent, non est huic simile: hoc habentibus pessimum est.
Quemadmodum Attalus noster dicere solebat, 'malitia ipsa maximam partem veneni sui bibit'.
Illud venenum quod serpentes in alienam perniciem proferunt, sine sua continent, non est huic simile: hoc habentibus pessimum est.
Source: Epistulae Morales ad Lucilium (Moral Letters to Lucilius), Letter LXXXI: On benefits, Line 22

“There are poisons that blind you, and poisons that open your eyes.”

“Better be poisoned in one's own blood then to be poisoned in one's principle.”
As quoted by Governor Barnett's Declaration to the Profile of Mississippi Broadcast via TV and Radio. Sep. 13, 1962 http://microsites.jfklibrary.org/olemiss/controversy/doc2.html without citation and in An unknown legend of India: A bharat ratna By Gaurav Pundeer https://books.google.com/books?isbn=3736889569
Famous speeches

“Be honey to those who seek your friendship, but deadly poison to those who dare attack you.”
https://www.nytimes.com/1975/03/26/archives/faisal-rich-and-powerful-led-saudis-into-20th-century-and-to-arab.html