Sentence:  But as to Man, all the Fruits of the Earth, all sorts of Herbs, Plants and Roots, the Fishes of the Sea, and the Birds of the Air do not suffice him, but he must disguise, vary, and sophisticate, change the substance into <WSD>accident</WSD>, that by such irritations as these, Nature might be provoked, and as it were necessitated. 
Meaning of the word marked with <WSD> tags:  Appearance, manifestation.