The Common Principles of Natural Philosophy

colored, when a strong solar ray passes through them, it is seen in an opaque medium from the side of the passing ray. But by touch we perceive the power of heat and other tangible things, and through smell we perceive the speciesoriginal: "speciem"; for Bacon, this is the "likeness" or "force" emitted by an object into the surrounding medium (like air) that allows it to be perceived or to act on other things. of odor, and through taste that of flavor, and through hearing the species of sound. And through the estimative poweroriginal: "estimativa virtus"; in medieval psychology, this is an internal sense that allows animals to perceive "intentions" (like friend or foe) that are not directly captured by the five senses. we perceive the species of bodily substances as useful or harmful, just as a sheep recognizes another sheep as its friend, and a wolf as an enemy.

And this is done through the power of the soul which is called "estimative," which is located in the posterior part of the brain, according to Avicenna in the first book of On the Soul original: "De Anima". And this species is a likeness of the entire composite agent, not only of its form, but also of its matter, because Aristotle holds in the first book of On the Soul that all action is due principally to the whole and secondarily to the form. Thus, it is more properly said that fire produces its species and effect through its form, just as a craftsman cuts with an axe, rather than saying the form of the fire itself acts. For form is the instrument of the agent, just as the axe belongs to the craftsman himself; and substanceoriginal: "substancia"; the fundamental reality or "thing-ness" of an object, as opposed to its temporary qualities. produces its species just as an accidentoriginal: "accidens"; a non-essential quality (like color, heat, or size) that depends on a substance to exist. does. For just as an accident cannot exist without a substance, neither can the species of an accident exist without the species of a substance.

For when the heat of fire acting upon air, water, wood, or any other thing produces a species of heat, its substantial nature likewise produces a species of its substance. This is first called "species" while it is incomplete, and afterward it becomes complete fire—namely, coal and flame. For otherwise, nothing would be produced in the world except accidents, because it is impossible for heat to generate the substantial nature of fire. This is because the generator is nobler than the 5 b r. generated, or at least equally noble, but every accident is infinitely distant from the nobility of substance. Therefore, nature first produces the species of substance, and secondarily the species of an accident; nor can it be otherwise, as I have demonstrated in the Metaphysics original: "Methaphisicis", and the singular thing produces...

9. Avicenna] On the Soul, p. 1, c. 5: "The estimative power is the power arranged at the top of the middle cavity of the brain, apprehending non-sensory 'intentions' that are in individual sensible things, like the power in the sheep judging that it must flee from this wolf and that it should have pity for this lamb," f. 5, ed. Venice, 1508. The editor notes that it is actually the memory power (vis memorialis) which is "in the posterior cavity of the brain" according to Avicenna, suggesting Bacon may have misremembered the specific location. 11-12 first book of On the Soul] apparently book ii, chapter 24.

The following are textual variations from different manuscript copies used by the 1909 editor:
1 them] Manuscript F reads "it" 4 first instance of "species"] Manuscripts read "species" (plural) 4-5 flavor . . . power] Omitted in Manuscript F 9 posterior] Manuscript F uses a slightly different Latin spelling 10 entire] Omitted in Manuscript D 13 it is said] Omitted in Manuscript D 14 its] Manuscript D adds "made" 16 himself] Manuscript D reads "is the instrument of himself" 17 just as an accident] Omitted in Manuscript D 27 nature] Manuscript M reads "multiplied" 29 as in] Manuscript D reads "for just as"