NEXT in order is the sensible faculty, which is as far beyond the other in dignity as a beast is preferred to a plant, having those vegetal powers included in it. 'Tis defined an "Act of an organical body by which it lives, hath sense, appetite, judgment, breath, and motion." His object in general is a sensible or passible quality, because the sense is affected with it. The general organ is the brain, from which principally the sensible operations are derived. This sensible soul is divided into two parts, apprehending or moving. By the apprehensive power we perceive the species of sensible things present, or absent, and retain them as wax doth the print of a seal. By the moving, the body is outwardly carried from one place to another; or inwardly moved by spirits and pulse. The apprehensive faculty is subdivided into two parts, inward or outward. Outward, as the five senses, of touching, hearing, seeing, smelling, tasting, to which you may add Scaliger's sixth sense of titillation, if you please; or that of speech, which is the sixth external sense, according to Lullius. Inward are three -- common sense, phantasy, memory. Those five outward senses have their object in outward things only and such as are present, as the eye sees no colour except it be at hand, the ear sound. Three of these senses are of commodity, hearing, sight, and smell; two of necessity, touch, and taste, without which we cannot live. Besides, the sensitive power is active or passive. Active in sight, the eye sees the colour; passive when it is hurt by his object, as the eye by the sun-beams. According to that axiom, Visibile forte destruit sensum (Too bright an object destroys the organ.) Or if the object be not pleasing, as a bad sound to the ear, a stinking smell to the nose, &c..
Sight.] Of these five senses, sight is held to be most precious, and the best, and that by reason of his object, it sees the whole body at once. By it we learn, and discern all things, a sense most excellent for use: to the sight three things are required; the object, the organ, and the medium. The object in general is visible, or that which is to be seen, as colour; and all shining bodies. The medium is the illumination of the air, which comes from light, commonly called diaphanum; for in dark we cannot see. The organ is the eye, and chiefly the apple of it, which by those optic nerves, concurring both in one, conveys the sight to the common sense. Between the organ and object a true distance is required, that it be not too near, nor too far off. Many excellent questions appertain to this sense, discussed by philosophers: as whether this sight be caused intra mittendo, vel extra mittendo, &c., by receiving in the visible species, or sending of them out, which Plato, Plutarch, Macrobius, Lactantius, and others dispute. And besides it is the subject of the perspectives, of which Alhazen the Arabian, Vitellio, Roger Bacon, Baptista Porta, Guidus Ubaldus, Aquilonius, &c., have written whole volumes.
Hearing.] Hearing, a most excellent outward sense, "by which we learn and get knowledge." His object is sound, or that which is heard; the medium, air; organ the ear. To the sound, which is a collision of the air, three things are required; a body to strike, as the hand of a musician; the body struck, which must be solid and able to resist; as a bell, lute-string, not wool, or sponge; the medium, the air; which is inward, or outward; the outward being struck or collided by a solid body, still strikes the next air, until it come to that inward natural air, which as an exquisite organ is contained in a little skin formed like a drum-head, and struck upon by certain small instruments like drum-sticks, conveys the sound by a pair of nerves, appropriated to that use, to the common sense, as to a judge of sounds. There is great variety and much delight in them; for the knowledge of which, consult with Boethius and other musicians.
Smelling.] Smelling is an "outward sense, which apprehends by the nostrils drawing in air;" and of all the rest it is the weakest sense in men. The organ in the nose, or two small hollow pieces of flesh a little above it: the medium the air to men, as water to fish: the object, smell, arising from a mixed body resolved, which, whether it be a quality, fume, vapour, or exhalation, I will not now dispute, or of their differences, and how they are caused. This sense is an organ of health, as sight and hearing, saith Agellius, are of discipline; and that by avoiding bad smells, as by choosing good, which do as much alter and affect the body many times, as diet itself.
Taste.] Taste, a necessary sense, "which perceives all savours by the tongue and palate, and that by means of a thin spittle, or watery juice." His organ is the tongue with his tasting nerves; the medium, a watery juice; the object, taste, or savour, which is a quality in the juice, arising from the mixture of things tasted. Some make eight species or kinds of savour, bitter, sweet, sharp, salt, &c., all which sick men (as in an ague) cannot discern, by reason of their organs misaffected.
Touching.] Touch, the last of the senses, and most ignoble, yet of as great necessity as the other) and of as much pleasure. This sense is exquisite in men, and by his nerves dispersed all over the body, perceives any tactile quality. His organ the nerves; his object those first qualities, hot, dry, moist, cold; and those that follow them, hard, soft, thick, thin, &c. Many delightsome questions are moved by philosophers about these five senses; their organs, objects, mediums, which for brevity I omit.