“Those diseases which medicines do not cure, iron cures; those which iron cannot cure, fire cures; and those which fire cannot cure, are to be reckoned wholly incurable.”
7:87
Variant translation: What cannot be cured by medicaments is cured by the knife, what the knife cannot cure is cured with the searing iron, and whatever this cannot cure must be considered incurable.
Aphorisms
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Hippocrates 33
ancient Greek physician -460–-370 BCRelated quotes
“Those who have the disease called Jesus will never be cured.”
The Relentless Tenderness of Jesus https://books.google.com/books?id=xvv4HcYdxd0C&pg=PA42&dq=%22Those+who+have+the+disease+called+Jesus+will+never+be+cured.%22&hl=en&sa=X&ved=2ahUKEwi9_f7L-JTkAhXJ1VkKHfSGDHUQ6AEwAXoECAEQAg#v=onepage&q=%22Those%20who%20have%20the%20disease%20called%20Jesus%20will%20never%20be%20cured.%22&f=false (1986), p. 42
1980s
Source: The Ragamuffin Gospel: Good News for the Bedraggled, Beat-Up, and Burnt Out

“There are no such things as incurable, there are only things for which man has not found a cure.”
Speech (30 April 1954)

Les médecins administrent des médicaments dont ils savent très peu, à des malades dont ils savent moins, pour guérir des maladies dont ils ne savent rien.
This attribution to Voltaire appears in Strauss' Familiar Medical Quotations (1968), p. 394, and in publications as early as 1956 http://books.google.pt/books?id=lCtCAQAAIAAJ&q=%22Doctors+are+men+who+prescribe+medicine+of%22&dq=%22Doctors+are+men+who+prescribe+medicine+of%22&hl=pt-PT&sa=X&ei=mbnWUsvDIfTB7Aaw_YD4Dw&redir_esc=y; the quotation in French does not, however, appear to be original, and is probably a relatively modern invention, only quoted in recent (21st century) published works, which attribute it to "Voltaire" without citing any source.
Attributed

“Yoga teaches us to cure what need not be endured and endure what cannot be cured.”
Source: Nancy Hine The Depression Trap: Ten Ways to Set Yourself Free http://books.google.co.in/books?id=7PxT2AJS_H4C&pg=PA61, Red Raft Publishing LLP, 2008, p. 61

On Milton (1825)

This attribution to Voltaire appears in Strauss' Familiar Medical Quotations (1968), p. 394, and in publications as early as 1956 http://books.google.pt/books?id=lCtCAQAAIAAJ&q=%22Doctors+are+men+who+prescribe+medicine+of%22&dq=%22Doctors+are+men+who+prescribe+medicine+of%22&hl=pt-PT&sa=X&ei=mbnWUsvDIfTB7Aaw_YD4Dw&redir_esc=y; the quotation in French does not, however, appear to be original, and is probably a relatively modern invention, only quoted in recent (21st century) published works, which attribute it to "Voltaire" without citing any source.
Original: (fr) Les médecins administrent des médicaments dont ils savent très peu, à des malades dont ils savent moins, pour guérir des maladies dont ils ne savent rien.