Montaigne is skeptical about medicine. He himself was ill, he suffered from kidney stones from 1577 onwards.
In the Essays, Montaigne in CHAPTER XXXVII, entitled “Of the resemblance of children to fathers”, gives a definition of health.
Doctors are not satisfied with having sickness in government, they make health sick, so that no season can escape their authority. From a constant and complete health, do they not draw the argument of a great future illness? I have been ill often enough: I have found, without their help, my illnesses as mild to bear (and have tried almost all kinds) and as short, as to no other: and if I have not measured the bitterness of their prescriptions. I have free and full health, without rules, and without any other discipline than my own custom and pleasure. Every place is good for me to stop: for I need no other conveniences when I am ill than those I need when I am healthy. I do not mind being without a doctor, without an apothecary, and without help: hence I see most of them more afflicted than ill. What? Do they themselves show us some happiness and duration in their lives, which can testify to some apparent effect of their science?
For Montaigne, health is a way of life. It is thus not contradictory with the disease. It is possible to live a normal life while being sick: health is thus only the acceptance of the disease. One passes into another way of life.
However, we must take a step back from what Montaigne writes, especially when he claims that he lives very well “without a doctor”, when in fact he often goes to the doctor.