98. Three Souls, Five Powers, and Four Grades of Life
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Main Topics #
The Problem: Three, Four, and Five #
Thomas Aquinas distinguishes:
- Three souls: vegetative, sensitive, rational
- Five genera of powers: vegetative (living), sensitive, appetitive, locomotive, intellectual
- Four grades of life: plant life, immobile animal life, mobile animal life, human life
The apparent contradiction requires explanation.
Rising Above Mere Matter #
Souls are fundamentally distinguished by how their operations transcend bodily nature:
Vegetative Soul (least immaterial): Uses bodily qualities and operations, yet has intrinsic principle of operation. Example: a tree grows both up and down, transcending the determination of non-living matter (which only goes up or down).
Sensitive Soul (more immaterial): Receives sensible forms without receiving matter. The sense receives the color of an object without becoming colored; a memory image has the shape of a face without being carved from bone or flesh.
Rational Soul (entirely immaterial): Understanding operates without any bodily organ; its object extends to all beings, including immaterial realities.
Why Five Powers Give Four Grades of Life #
Appetitive powers do not constitute a separate grade of life because they necessarily accompany knowing powers:
- Whatever has sensation also has pleasure/pain and desire
- Whatever has understanding also has will
- Therefore, appetite is never found without a knowing power
Locomotive power (motion from place to place) does not constitute a distinct transcendence of matter because non-living things (e.g., automobiles) also move. The distinction lies in whether the power itself rises above matter, not in the external manifestation.
Why Four Grades Give Three Souls #
The three souls are distinguished by three distinct ways of rising above bodily nature, not by the number of powers:
- The vegetative soul rises above matter minimally
- The sensitive soul rises above matter significantly more
- The rational soul rises above matter entirely
These represent three qualitatively distinct levels of transcendence.
Key Arguments #
The Immateriality of Sensation (Shower Example) #
- When first entering hot water, one feels the external heat of the water
- After acclimation, the heat becomes one’s own bodily heat and is less intensely sensed
- This shows two types of reception: receiving the heat as external quality vs. receiving it as one’s own state
- Sensation receives the form of external objects immaterially, unlike digestion which uses bodily chemical processes
The Object Determines the Power #
- Powers are distinguished by their objects (acts are determined by objects)
- Higher powers have more universal objects:
- Vegetative powers: only the body united to the soul
- Sensitive powers: sensible bodies (including external bodies)
- Intellectual powers: all beings, including immaterial realities
Two-fold Relation to External Objects #
For powers dealing with objects beyond one’s own body:
Knowing powers: The external object comes into the soul through likeness
- Sensation: receiving external sensible qualities
- Understanding: receiving all beings
Desiring powers: The soul tends toward the external object
- Desire: regarding the object as an end
- Locomotion: regarding the object as the limit of motion
Knowledge vs. Love: A Fundamental Contrast #
- Knowing: Brings the external into oneself (like trying to fit the ocean into one’s mind)
- Loving: Goes out toward the external object (like jumping into the ocean)
- The truth is primarily in the mind; the good is in things
- Love is said to be in the thing loved; the lover’s heart goes out to the beloved
Important Definitions #
Rising above matter (ἀνάβασις/transcendentia): The characteristic by which a soul or power transcends the limitations of non-living material nature. Three distinct degrees exist in living things.
Immaterial reception: The way sensation and understanding receive the form of an object without receiving its matter. Example: the eye receives color without becoming colored.
Intrinsic principle: An operation that proceeds from within the thing itself, not from an external source. All living operations have this character, distinguishing them from non-living processes.
Examples & Illustrations #
The Shower and Ocean Examples #
- Man entering hot shower experiences the water’s heat as external, then acclimation reduces the sensation as the heat becomes his own body temperature
- Similarly, gradual entry into cold ocean water: intense cold sensation at first, then acclimation
- Illustrates how sensation receives external qualities immaterially, distinct from bodily physical reception
The Ocean and the Mind (Augustine) #
- Augustine responds to a child trying to fit the ocean into a hole in the sand
- Child replies: “Neither can you fit the Trinity into your mind”
- Illustrates the limitation of knowing (bringing externals into oneself) versus loving (going out to the object)
The Tree’s Growth #
- A tree grows both upward and downward, transcending the determination of non-living matter
- Non-living bodies either move up (air, fire) or down (earth, water) when left to themselves
- The tree’s intrinsic principle of operation allows contrary motions, showing transcendence of mere material nature
Digestion and Chemical Processes #
- Digestion uses heat and chemical processes to break down food
- These same chemical processes could theoretically be replicated in non-living matter
- Yet digestion is organized in a unique way by the living thing; chemicals serve the soul’s power
- Shows vegetative operations use bodily qualities but maintain intrinsic principle of operation
Personal Anecdotes #
- Nephew’s sensory and intellectual response to encountering a person of different race for the first time: different smells, sights, and intellectual processing occurring simultaneously
- Child with toy: senses act first, then desire, then voluntary motion to grasp
- Man with friend Francis from Ghana: the friend’s smile made a positive first impression, contrasting with the instructor’s childhood experience where a child was taught that dark skin was dirty
Heat and Cold as Metaphors for Love and Knowledge #
- Hot expands and overflows (like love going out to others)
- Cold contracts and concentrates (like reason withdrawing into itself)
- Love: “My heart goes out to you” (overflowing, expansion)
- Knowledge: concentration, meditation (withdrawing, contraction)
- Body temperature drops during concentrated thinking
Questions Addressed #
Q: Why do we distinguish three souls if there are five powers? A: Souls are distinguished by how their operations rise above mere bodily matter, not by counting powers. Three distinct ways of transcendence exist: vegetative (least), sensitive (more), rational (entirely). The five powers serve these three fundamental distinctions.
Q: Why are there only four grades of life despite five powers? A: Appetitive powers always accompany knowing powers. Whatever has sensation also has appetite; whatever has understanding also has will. Therefore, appetite does not add a new grade of life.
Q: Why doesn’t locomotive power constitute a separate soul or grade? A: Locomotion does not itself represent a distinct rising above matter, as non-living things (automobiles) also move. The distinction lies in how the power itself transcends bodily nature, not in the external manifestation of motion.
Q: How is sensation more immaterial than digestion? A: Digestion uses bodily chemical qualities in their material reality. Sensation receives the form of an object without receiving its matter (the eye sees color without becoming colored, memory holds a face’s shape without bone or flesh). This immaterial reception distinguishes sensation as more transcendent than digestion.
Q: How do knowing and loving relate differently to external objects? A: Knowing brings the external object into the knower through likeness. Loving goes out to the object itself. Knowledge tries to contain; love goes out from itself. This is why love is more proportioned to God in this life: one cannot adequately contain God in one’s mind, but one’s will can go out to God as He is.
Notable Quotes #
“The truth is primarily in the mind, but the good is in things.” — Aristotle (cited on the fundamental difference between knowledge and love)
“My heart goes out to you.” — Common expression illustrating the nature of love as going out to the object, referenced repeatedly
“Where your treasure is, there your heart shall be.” — Christ (cited to show that love is located in the thing loved, not in the lover)
“The soul is more where it loves than where it animates.” — Augustine, ubi amat quam manimat (Latin, cited on the priority of love over mere animation)
“Lovers and madmen have such seething brains, such shaping fantasies that apprehend more than cool reason ever comprehends.” — Shakespeare (cited on the expansiveness of love vs. the concentration of reason)