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INTRODUCTION.
5

Italic textby the eminent men here alluded to (Hunter and Barclay, Bichât and Cuvier) may well be collated with those of Aristotle, who wrote at a time when science was in its infancy, and when, for profitable investigation, he had to depend almost exclusively, amid so much hypothesis, upon his own laborious and perspicacious intellect.

In quoting those writers, there is hardly occasion for observing any order of precedence, as they flourished about the same time, and contributed equally to the present development of physiological science.

According to Hunter[1], "Animal matter is endowed with a principle called, in common language, life. This principle is perhaps conceived of with more difficulty than any other in nature, which arises from its being more complex in its effects than any other; and it is, therefore, no wonder that it is the least understood. But, although life may appear compounded in its effects in a complicated animal like man, it is as simple in him as in the most simple animal, and is reducible to one simple property in every animal." In another paragraph, he adds, "the first and most simple idea of life is its being the principle of self-preservation, by its preventing

  1. On Vital Principle