If we were even assured that, when they make a mistake, that mistake of theirs would do us no harm, though it did us no good, it were a reasonable bargain to venture the making ourselves better without any danger of being made worse. AEsop tells a story, that one who had bought a Morisco slave, believing that his black complexion had arrived by accident and the ill usage of his former master, caused him to enter with great care into a course of baths and potions: it happened that the Moor was nothing amended in his tawny complexion, but he wholly lost his former health. How often do we see physicians impute the death of their patients to one another? I remember that some years ago there was an epidemical disease, very dangerous and for the most part mortal, that raged in the towns about us: the storm being over which had swept away an infinite number of men, one of the most famous physicians of all the country, presently after published a book upon that subject, wherein, upon better thoughts, he confesses that the letting blood in that disease was the principal cause of so many mishaps. Moreover, their authors hold that there is no physic that has not something hurtful in it. And if even those of the best operation in some measure offend us, what must those do that are totally misapplied? For my own part, though there were nothing else in the case, I am of opinion, that to those who loathe the taste of physic, it must needs be a dangerous and prejudicial endeavour to force it down at so incommodious a time, and with so much aversion, and believe that it marvellously distempers a sick person at a time when he has so much need of repose. And more over, if we but consider the occasions upon which they usually ground the cause of our diseases, they are so light and nice, that I thence conclude a very little error in the dispensation of their drugs may do a great deal of mischief. Now, if the mistake of a physician be so dangerous, we are in but a scurvy condition; for it is almost impossible but he must often fall into those mistakes: he had need of too many parts, considerations, and circumstances, rightly to level his design: he must know the sick person's complexion, his temperament, his humours, inclinations, actions, nay, his very thoughts and imaginations; he must be assured of the external circumstances, of the nature of the place, the quality of the air and season, the situation of the planets, and their influences: he must know in the disease, the causes, prognostics, affections, and critical days; in the drugs, the weight, the power of working, the country, figure, age, and dispensation, and he must know how rightly to proportion and mix them together, to beget a just and perfect symmetry; wherein if there be the least error, if amongst so many springs there be but any one out of order, 'tis enough to destroy us. God knows with how great difficulty most of these things are to be understood: for (for example) how shall the physician find out the true sign of the disease, every disease being capable of an infinite number of indications? How many doubts and controversies have they amongst themselves upon the interpretation of urines? otherwise, whence should the continual debates we see amongst them about the knowledge of the disease proceed? how could we excuse the error they so oft fall into, of taking fox for marten? In the diseases I have had, though there were ever so little difficulty in the case, I never found three of one opinion: which I instance, because I love to introduce examples wherein I am myself concerned.
A gentleman at Paris was lately cut for the stone by order of the physicians, in whose bladder, being accordingly so cut, there was found no more stone than in the palm of his hand; and in the same place a bishop, who was my particular friend, having been earnestly pressed by the majority of the physicians whom he consulted, to suffer himself to be cut, to which also, upon their word, I used my interest to persuade him, when he was dead and opened, it appeared that he had no malady but in the kidneys. They are least excusable for any error in this disease, by reason that it is in some sort palpable; and 'tis thence that I conclude surgery to be much more certain, by reason that it sees and feels what it does, and so goes less upon conjecture; whereas the physicians have no 'speculum matricis', by which to examine our brains, lungs, and liver.
Even the very promises of physic are incredible in themselves; for, having to provide against divers and contrary accidents that often afflict us at one and the same time, and that have almost a necessary relation, as the heat of the liver and the coldness of the stomach, they will needs persuade us, that of their ingredients one will heat the stomach and the other will cool the liver: one has its commission to go directly to the kidneys, nay, even to the bladder, without scattering its operations by the way, and is to retain its power and virtue through all those turns and meanders, even to the place to the service of which it is designed, by its own occult property this will dry-the brain; that will moisten the lungs. Of all this bundle of things having mixed up a potion, is it not a kind of madness to imagine or to hope that these differing virtues should separate themselves from one another in this mixture and confusion, to perform so many various errands? I should very much fear that they would either lose or change their tickets, and disturb one another's quarters. And who can imagine but that, in this liquid confusion, these faculties must corrupt, confound, and spoil one another? And is not the danger still more when the making up of this medicine is entrusted to the skill and fidelity of still another, to whose mercy we again abandon our lives?