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Notes
Note 1, p. 114. Colour, however, is not thus made visible.] The opinion here objected to originated with Democritus. Aristotle[1] held it to be absurd to suppose that colour and vision could be a process of emanation from the eyes; for colour produces sensation, he observes, not by emanation but, by contact, and so it is better, at once, to admit that vision is produced by the action of the medium. There are[2], it is said, seven distinctions of colour and as many of savour; and in another work[3] seven vowels, seven pleiads, and seven chords.
Note 2, p. 114. No object, however, which is without humidity.] This is little more than a repetition of what had been said concerning sapid substances. Aristotle[4] seems to have adopted a theory, derived from mechanics, for explaining the solubility of objects--Whence comes it, he asks, that an earth is both melted and moistened by fluid (καὶ τήκεται καὶ τέγγεται) while soda (τὸ δὲ νίτρον) is melted but not moistened? The answer is, because there are pores throughout the soda which cause its parts to be, at once, separated by the fluid; while the pores in the earth are in alternate rows, so that the influence of the fluid, in whatever way it may gain access, cannot but be different.
Note 3, p. 114. As vision is perceptive, &c.] The argument here is interrupted and obscured by parenthetical explanations; but the purport is, that the senses are the sole judges of sentient impressions through all their degrees of intensity, and that, as sensibility is a mean, they cannot discriminate such as are far above or below the allotted medial standard. There is a seeming discrepance, however, in employing the term invisible as analogous to impossible on other subjects, as vision is not altogether lost in any darkness; but a creature without feet could not continue its existence, nor a fruit without the kernel continue its species.
Note 4, p. 115. The impotable as well as the potable, &c.] The impotable implies, of course, whatever is neither moist nor capable of becoming moist, and every such substance must, necessarily, pain—be very disagreeable to, that is—and pervert the Taste. All these passages, however, while proving that moisture is required for savour, point to a want of knowledge of the salivary and mucous glands which were yet to be discovered. But over and above the due conditions of moisture, there was still required the knowledge of the nervous system to account for the many perversions of Taste which are manifested, both in sick and well; and manifested, at times, without any apparent cause. It will occur to many, besides, how differently the Taste is affected by the same substance, as sugar for instance, in different persons, and even, at times, in the same person.
Note 5, p. 116. Kinds of savour are like shades of colour, &c.] There must ever be difficulty in fixing upon terms for savours or other sentient qualities, and still greater difficulty in settling what are the exact equivalents for such terms in another, and that not a cognate tongue; for although some savours, as bitter and sweet, may be supposed to have an universal acceptation, there are others which, being far less definite, are subject to variation, according to climate and race. So that, with the exception of bitter and sweet, it can hardly be pretended that the other terms, as oily, pungent, rough, astringent, &c., are perfect representatives of those in the text.
Note 6, p. 116. In fine the sapid sense, &c.] This passage does but repeat what has been already insisted upon, that the sense, in potentiality, that is, when inactive, is identical with that which is to act upon it; but that, having been acted upon, it is brought into the state of reality, and then becomes perceptive of the qualities of the excitant.
- ↑ De Sensu et Sens. 3. 15.
- ↑ De Sensu et Sens. 4. 18.
- ↑ Metaphysica. XIII. 6. 5.
- ↑ De Meteorol. IV. 9. 4.