Although the title given to this version embodies, as I believe, Aristotle's idea, yet it is not pretended that the writers cited by him always employed the term ψυχή in his sense; or even that he, himself, was always consistent in the use of it. Plato was certainly not engaged upon material agencies or properties in his Phædo, and in the Timæus, which partakes of a physiological character, and as such has been criticised in this Treatise, the animating motor principle is treated of rather as an abstraction than as the originating and natural cause of life, through all its manifestations. The term Vital Principle, however, has been retained throughout, even where it may seem to be less apposite, as well to avoid the misapprehension which might be occasioned by the substitution of another term, (that of soul I mean,) which might then to some appear to be its synonym, as on account of the extreme difficulty of determining the point where the metonymy might, without question, be adopted.
This Translation is from the Oxford edition, collated with that of Trendelenburg; and this allusion to that eminent scholar affords me the opportunity of acknowledging the assistance which has been derived from his comments upon passages, which require, for elucidation, all the light that can be thrown upon them by tradition and learning.
