XLVIII. Besides this, some express a doubt, whether plants are vegetable or not; and some are also doubtful, whether the property of vegetation does not likewise belong to stones and metals. If we consult the Cartesians upon this point, they will tell us, that all we call vegetation or nutrition of plants, is pure mechanism, and that the attraction of the nutritious juice which we attribute to them, is a solemn chimera. If we forsake the Cartesians, and apply to the experimental philosophers, we shall find many of them, who will tell us, that metals and stones grow by means of vegetation; which is an opinion, that not long ago, was illustrated by Joseph Pitton de Tournfort, a celebrated naturalist of the Academy Royal of Sciences at Paris, and more especially, by the celebrated observations he made upon marble in the wonderful cave of Antiparos; and with respect to metals, we, to the authority of others, shall add that of Aristotle, who in his book _de Mirabilibus Auscultationibus_, says, that in a territory of the island of Cyprus, they were used to sow iron, and that it grew and vegetated like other plants. XLIX. And now we are speaking of Aristotle, we will not omit mentioning an authority of his, which is very applicable to our present subject, because it is totally opposite to a received opinion in the schools, to wit, that plants and animals are of two different genuses, and that the distinction between them is, that the animal is a living sensible entity, and the plant a living insensible one. Aristotle in his book _de Plantis_ says, that oysters and other shell-fish, are both plants and animals: _scimus autem, quod conchyla animalia sunt cognitione carentia: quapropter plantæ sunt, & animalia_. I ask now, how one species can be classed under two diametrically opposite genuses? and how an oyster can be both sensible and insensible? for as an animal, it ought to be a living sensible entity, and as a plant, a living insensible one. Nor can it be said, that Aristotle, when he called an oyster a plant, spoke in a metaphorical sense, for this mode of speaking is not allowed to philosophers, but is only permitted to poets and orators. Besides, the cause he assigns, shews, that he spoke in a rigorous philosophical sense; although, to speak the truth, I do not comprehend who could reveal to Aristotle, that oysters and other shell-fish are destitute of that sort of knowledge, which is proper and natural to the most stupid brutes. SECT. XII. L. From the lowest species, we proceed to the next above, and enquire, what is the nature of a living entity; what we are to understand by the term living, and what is life? To this, we shall be answered from the schools, that life is motion _ab intrinsico_, and that living, means that which moves _ab intrinsico_; that is, its motion is produced by some intrinsic faculty, or virtue, which it has within itself.