22. The Nutritive Soul: Food, Growth, and Generation

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Lecture Notes

Main Topics #

Refutation of Materialist Accounts of Life #

Empedocles’ Error #

• Empedocles attempted to explain plant growth by reference to the four elements alone: earth naturally descends, fire naturally ascends
• The problem: This fails to account for the unity and ordered structure of living things
• The plant’s roots are analogous to the animal’s head—both are organs of nutrition, demonstrating purposive organization that mere elemental forces cannot explain
• Living things grow to a determinate limit and maintain a determinate shape, unlike fire which grows indefinitely wherever fuel exists

The Fire Theory #

• Some ancients attributed life to fire because fire appears to grow, consume, and generate
• Aristotle’s response: Fire might function as an instrument (ὄργανον) of the nutritive soul, but cannot be its cause
• Fire lacks the ordering principle characteristic of living growth: it consumes indiscriminately and grows without limit
• Living things exhibit ratio (λόγος/proportion) and limit (πέρας) in their growth—evidence of formal causation by the soul

Food as the Proper Object of the Nutritive Power #

Food in Two Respects #

• Food must be understood in two distinct ways:
  • As undigested (ἀπέπτως): Food is initially unlike (ἀνόμοιον) or contrary to the fed thing; transformation occurs between contraries
  • As digested (πέπεπτως): Food becomes like (ὅμοιον) the fed thing; it is assimilated into the body’s substance
• Both ancient opinions (that food is like the fed, and that it is unlike) speak rightly, but not in the same respect

The Three Operations and Food #

Food relates distinctly to the three acts of the nutritive soul:

• Feeding/Preservation (τροφή): Food as a “this something” (τόδε τι/individual substance) preserves the substance of the living thing
• Growth (αὔξησις): Food as quantity (ποσόν) contributes to increase in size
• Generation/Reproduction (γένεσις): The excess of food beyond preservation and growth is directed toward generating another like oneself

The Definition of the Nutritive Soul by Its Ultimate Act #

Why Generation, Not Feeding or Growing? #

• The nutritive soul has three operations: feeding, growing, and generating
• Aristotle defines the soul by its ultimate or highest operation—generation (reproduction)
• A living thing feeds itself and grows itself, but it only generates another like itself
• This mirrors how reason is defined by “large discourse” (large discourse reveals reason’s full capacity more than small discourse)

Metaphysical Significance #

• Mortal things cannot persist individually forever, so they perpetuate themselves through reproduction
• In generating another like itself, a mortal thing strives to be immortal and divine (ἀεί, θεῖον) so far as possible
• This reflects Platonic insight: all things desire to be like God through generation

Key Arguments #

Against Pure Materialism #

Premise 1: Living things exhibit determinate form, proportion (ratio), and limit in their growth
Premise 2: Purely material forces (like fire or elemental tendencies) cannot account for such ordered structure
Conclusion: A non-material principle (the soul as form) must be the cause of life’s organization

For Food as Proper Object #

Premise 1: Every power has a proper object (as sight has color)
Premise 2: The nutritive power operates on food
Premise 3: Objects must be understood before powers, and powers before acts
Conclusion: Food is the proper object of the nutritive power and must be analyzed first

For the Dual Nature of Food #

Premise 1: Change occurs between contraries
Premise 2: The body acts upon food, transforming it
Premise 3: After digestion, food is assimilated into the body
Conclusion: Food is unlike (contrary to) the fed as undigested, but like the fed when digested

For Defining by Generation #

Premise 1: Things are properly defined by their ultimate or most complete operation
Premise 2: The nutritive soul can preserve itself (feeding) and increase itself (growth), but only generate another
Conclusion: The nutritive soul is properly defined as the generative soul (ψυχή γεννητική)

Important Definitions #

Soul (ψυχή/anima) #

• In context: The principle that unifies contrary elements (fire and earth) in the body and accounts for ordered growth
• As cause: The soul operates as form (what makes the body alive), as mover (principle of motion), and as end (purpose)

Nutritive Soul (ψυχή θρεπτική) #

• The power of the soul enabling feeding, growth, and reproduction
• Present in all living things (plants, animals, humans)
• Defined ultimately by its act of generation (γένεσις)

Food (τροφή) #

• That which preserves the substance of a living thing and enables growth
• Dual nature: undigested food is unlike (ἀνόμοιον) the fed; digested food is like (ὅμοιον) the fed
• The proper object of the nutritive power, just as color is the object of sight

Generation (γένεσις) #

• The production of another living thing similar to the generating thing
• The ultimate act of the nutritive soul
• The way mortal things approach immortality and participate in the divine

Ratio/Proportion (λόγος) #

• The ordered measure and determinate limit that characterizes living growth
• Distinguishes organized growth (in living things) from unlimited growth (in fire)

Examples & Illustrations #

The Forest Fire (Colorado) #

• Forest fires spread indefinitely as long as fuel (dry forest) exists
• Contrasts sharply with living growth: a tree grows to a determinate height and maintains a determinate shape
• Fire consumes whatever is present without order; a tree’s thousands of leaves each maintain the same shape for that species
• Demonstrates why fire cannot be the cause of life

The Brick Wall vs. The Tree #

• A brick wall gets higher when bricks are added externally (external addition)
• A tree grows by taking in materials and building itself up from within (organic growth)
• Shows the fundamental difference between artificial accumulation and natural, ensouled growth

The Immigrant Families #

• Children of immigrants often grow taller than their parents due to better nutrition
• Illustrates how food, as quantity, contributes to growth
• Shows the distinction between feeding (preservation of substance) and growing (increase in quantity)

Shakespeare’s Much Ado About Nothing #

• Beatrice says of Benedict: “is it possible disdain should die while she has such meat food to feed it as senior benedict?”
• Illustrates metaphorical use of “feeding” to denote the object of a passion or emotion
• Shows how familiar the concept of food-as-object is: we naturally apply it to passions and thoughts

The White Castle Robbery #

• A robber attempts robbery but fails to control the bag; he runs away, realizing he doesn’t have a gun
• He is angered at himself—not for attempting robbery, but for being stupid (defect of reason)
• Illustrates why defects of reason (stupidity) are more shameful than defects of will (wickedness)
• Shows why intemperance is more shameful than anger: it more completely extinguishes reason

Biblical Metaphors of Feeding #

• Jesus at the well: “My food is to do the will of my Father” (Gospel of John)
• The Psalms: “My flesh hungers, my soul thirsts for you” (Psalm 42-43)
• These express the intensity of desire through the metaphor of hunger and thirst
• Demonstrates that the concept of food-as-object extends to spiritual and rational desires

Questions Addressed #

How can the soul hold together contrary elements like fire and earth? #

Answer: The soul is a unifying principle (cause) that holds contrary elements in an ordered whole. Unlike Empedocles, who could not explain this unity through elements alone, the soul accounts for the determinate shape, proportion, and limit in living growth.

Why do some say food is like the fed, while others say it is unlike? #

Answer: Both are correct in different respects. As undigested, food is unlike (contrary to) the fed thing because change occurs between contraries. As digested and assimilated, food becomes like the fed thing. The confusion arises from not distinguishing these two stages of food’s relation to the living body.

Could fire be the cause of life, given that it appears to grow and digest? #

Answer: Fire might be an instrument of the nutritive soul, but not its primary cause. Fire grows without limit wherever fuel exists; living things grow to a determinate limit. Fire consumes indiscriminately; living things maintain determinate form and shape. Fire lacks the ratio (proportion) and limit that characterize living growth, which come from the soul as form.

Why is the nutritive soul defined by generation rather than by feeding or growing? #

Answer: Things are properly defined by their ultimate or highest operation. A living thing can feed itself and grow itself, but only generates another like itself. Generation reveals the full power of the nutritive soul—the way mortal things approach immortality by perpetuating their kind.

Connections to Theology #

The Sacraments of Christian Initiation #

Berquist notes that Thomas Aquinas organizes three sacraments in correspondence with the three powers of the nutritive soul:

• Baptism ↔ Generation: Being born again in Christ (John 3:3-5: “Unless a man be born again…”)
• Confirmation ↔ Growth: Spiritual strengthening and maturation for witnessing to Christ
• Eucharist ↔ Feeding: Spiritual nourishment of the soul by the body and blood of Christ

This correspondence shows how understanding natural philosophy (the nutritive soul) illuminates theological mysteries. Christ as the Word made flesh conveys spiritual realities through material means—just as the soul works through the body’s material form.