ACCORDING to Aristotle, the soul is defined to be εντελεχεια (entelecheia), perfectio et actus primus corporis organici, vitam habentis in potentia: the perfection or first act of an organical body, having power of life, which most philosophers approve. But many doubts arise about the essence, subject, seat, distinction. and subordinate faculties of it. For the essence and particular knowledge, of all other things it is most hard (be it of man or beast) to discern, as Aristotle himself; Tully, Picus Mirandula, Tolet, and other Neoteric philosophers confess:--"We can understand all things by her, but what she is we cannot apprehend." Some therefore make one soul, divided into three principal faculties; others, three distinct souls Which question of late hath been much controverted by Picolomineus and Zabarel. Paracelsus will have four souls, adding to the three grand faculties a spiritual soul: which opinion of his, Campanella, in his book de sensu rerum, much labours to demonstrate and prove, because carcasses bleed at the sight of the murderer; with many such arguments: And some again, one soul of all creatures whatsoever, differing only in organs; and that beasts have reason as well as men, though, for some defect of organs, not in such measure. Others make a doubt whether it be all in all, and all in every part; which is amply discussed in Zabarel amongst the rest. The common division of the soul is into three principal faculties -- vegetal, sensitive, and rational, which make three distinct kinds of living creatures -- vegetal plants, sensible beasts, rational men. How these three principal faculties are distinguished and connected, Humano ingenio inaccessum videtur, is beyond human capacity, as Taurellus, Philip, Flavius, and others suppose. The inferior may be alone, but the superior cannot subsist without the other; so sensible includes vegetal, rational both; which are contained in it (saith Aristotle) ut trigonus in tetragono, as a triangle in a quadrangle.
Vegetal Soul.] Vegetal, the first of the three distinct faculties, is defined to be "a substantial act of an organical body, by which it is nourished, augmented, and begets another like unto itself" In which definition, three several operations are specified --altrix, auctrix, procreatrix; the first is nutrition, whose object is nourishment, meat, drink, and the like; his organ the liver in sensible creatures; in plants, the root or sap. His office is to turn the nutriment into the substance of the body nourished, which he performs by natural heat. This nutritive operation hath four other subordinate functions or powers belonging to it -- attraction, retention, digestion, expulsion.
Attraction.] Attraction is a ministering faculty, which, as a loadstone doth iron, draws meat into the stomach, or as a lamp doth oil; and this attractive power is very necessary in plants, which suck up moisture by the root, as another mouth, into the sap, as a like stomach.
Retention.] Retention keeps it, being attracted into the stomach, until such time it be concocted; for if it should pass away straight, the body could not be nourished.
Digestion.] Digestion is performed by natural heat; for as the flame of a torch consumes oil, wax, tallow, so doth it alter and digest the nutritive matter. Indigestion is opposite unto it, for want of natural heat, Of this digestion there be three differences -- maturation, elixation, assation.
Maturation.] Maturation is especially observed in the fruits of trees; which are then said to be ripe, when the seeds are fit to be sown again. Crudity is opposed to it, which gluttons, epicures, and idle persons are most subject unto, that use no exercise to stir natural heat, or else choke it, as too much wood puts out a fire.
Elixation.] Elixation is the seething of meat in the stomach, by the said natural heat, as meat is boiled in a pot; to which corruption or putrefaction is opposite.
Assation.] Assation is a concoction, of the inward moisture by heat; his opposite is a semiustulation.
Order of Concoction four-fold.] Besides these three several operations of digestion, there is a four-fold order of concoction:-- mastication, or chewing in the mouth; chilification of this so chewed meat in the stomach; the third is in the liver, to turn this chylus into blood, called sanguification; the last is assimulation, which is in every part.
Expulsion.] Expulsion is a power of nutrition, by which it expels all superfluous excrements, and reliques of meat and drink, by the guts, bladder, pores; as by purging, vomiting, spitting, sweating, urine, hairs, nails, &c.
Augmentation.] As this nutritive faculty serves to nourish the body, so doth the augmenting faculty (the second operation or power of the vegetal faculty) to the increasing of it in quantity, according to all dimensions, long, broad, thick, and to make it grow till it come to his due proportion and perfect shape; which hath his period of augmentation, as of consumption; and that most certain, as the poet observes:--
"Stat sua cuique dies, breve et irreparabile tempus
Omnibus est vitæ"--
"A term of life is set to every man,
Which is but short, and pass it no one can."
Generation.] The last of these vegetal faculties is generation, which begets another by means of seed, like unto itself to the perpetual preservation of the species. To this faculty they ascribe three subordinate operations:-- the first to turn nourishment into seed, &c.
Life and Death concomitants of the Vegetal Faculties.] Necessary concomitants or affections of this vegetal faculty are life and his privation, death. To the preservation of life the natural heat is most requisite, though siccity and humidity, and those first qualities, be not excluded. This heat is likewise in plants, as appears by their increasing, fructifying, &c., though not so easily perceived. In all bodies it must have radical moisture to preserve it, that it be not consumed; to which preservation our clime, country, temperature, and the good or bad use of those six non-natural things avail much. For as this natural heat and moisture decays, so doth our life itself; and if not prevented before by some violent accident, or interrupted through our own default, is in the end dried up by old age, and extinguished by death for want of matter, as a lamp for defect of oil to maintain it.