Internal criticism

0Charles Sanders Peirce wrote:02br
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00"The last fifty years have taught the lesson of not trifling with facts and not trusting to principles and methods which are not logically founded upon facts and which serve only to exclude testimony from consideration. 02br
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00"Such, for example, was the dictum of Claude Bernard that a disease is not an entity — a purely metaphysical doctrine. But the observation of facts has taught us that a disease is in many, if not most, serious cases, just as much an entity as a human family consisting of father, mother, and children. 02br
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00(...)02br
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00"Such were the dicta by means of which 01b01u00the internal criticism02u02b00 of historical documents was carried to such a height that it often amounted to the rejection of all the testimony that has come down to us, and the substitution for it of a dream spun out of the critic's brain. But archeological researches have shown that ancient testimony ought to be trusted in the main, with a small allowance for the changes in the meanings of words." 02br
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00Would you please explain what "01b00the internal criticism"02b00 means in this context? 02br
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00Thank you.02br
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00Cadzao0-