293. The Soul's Essence and Grace: Species, Powers, and Properties

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Lecture Notes

Main Topics #

The Soul’s Essence vs. Powers #

• The soul’s essence (or nature) is prior to its powers in a threefold sense:
  1. Logically: the essence can be understood without the powers
  2. Causally: the essence is the cause from which powers naturally flow
  3. Epistemologically: we know the soul through its powers and their acts (following Aristotle)
• Powers are natural properties following upon the species, not constituting it
• A thing is not defined or constituted in its species through its powers, but the reverse

The Distinction of Souls by Species #

• Three kinds of soul exist in a hierarchy: plant soul (lowest), animal soul (middle), human/rational soul (highest)
• These are distinguished not by their powers but by their essential nature
• The human soul differs in species from brute animals and plants by its rational nature
• Not every soul is capable of grace; only the rational soul is, because grace belongs to the soul “insofar as it is of this particular species”
• The whole power the soul can have is found in man; less in animals; even less in plants

Grace and the Soul’s Essence #

• Grace resides in the essence of the soul, not merely in its powers
• The soul is the subject of grace “according as it is in the species of understanding or rational nature”
• Because grace belongs to the rational soul’s essence, it does not follow that all souls are capable of grace
• The relationship mirrors how man has senses because he is an animal (all animals have senses), but man has reason not because he is an animal but because he is a man

Life and Motion as Known Through Effects #

• We know the soul through its powers and these powers through their acts, and acts through their objects
• The most manifest signs of life are:
  • Growth in plants (continuous change in quantity)
  • Locomotion in animals (continuous local motion)
• These are the clearest examples because they involve continuous quantity, which is most sensible to us
• Operations like understanding, sensing, and loving are “motions” only in an analogous sense—they are perfect acts (not imperfect like walking home)
  • A perfect act: when you hear, you have heard; when you understand, you understand; when you love, you have loved
  • An imperfect act: when you walk home, you have not yet walked home

Reasoning from Properties Back to Species #

• One cannot say a thing has a property because of another property
• Example: Two is not two “because it is half of four”; rather, it is half of four because it is two
• Two is also a third of six, a fourth of eight, a fifth of ten—these are not the same relations, but they all follow from its being two
• Similarly, the soul’s powers (reason, will, etc.) all follow from the soul’s essential nature or species, not the reverse

The Definitions of Reason #

• Berquist offers two compatible definitions:
  1. “The ability to understand and reason and order itself in others”
  2. Shakespeare’s definition: “The ability for large discourse, looking before and after”
• Reason is “the only part of us that can know itself”; the hand does not know what a hand is, nor the eye what an eye is
• Aristotle shows in Book III of the Soul that reason cannot be a body because it understands universals and engages in “large discourse,” operations not confined to bodily parts

The Immersion of the Soul in the Body #

• The animal soul is “entirely immersed in the body”
• The human soul is “partly in the body but partly above the body”
• This is because the human intellect has operations not dependent on matter (understanding universals)
• Therefore, the soul’s being cannot be entirely bound to or dependent on the body

Key Arguments #

Third Objection and Its Resolution #

Objection: Not every soul is capable of grace; therefore the essence of the soul is not the proper subject of grace.

Thomas’s Response:

• The soul is subject of grace according as it is in the species of rational nature
• Powers are natural properties following upon the species; they do not constitute the species
• The soul differs in species from animal and plant souls through its essential nature, not through powers
• Therefore, if the essence of the human soul is the subject of grace, it does not follow that every soul can be the subject of grace
• This is solved “easily” because it concerns what belongs to the essence “insofar as it is of this particular species”

The Analogy of Mathematical Properties #

Example: Four is an even number because it is a number and belongs to the species “four” (which is even), not because there are numbers that aren’t even.

Application:

• Four is half of eight because it is the particular species/number four
• Four is also a third of twelve, a fourth of sixteen—but these are all consequences of its being four
• The soul has reason/powers because it is the species “human soul,” not because it is a soul universally
• Just as “having interior angles equal to two right angles” is a property of the species triangle (not of “rectilineal plane figure” generally)

The Analogy of Man and Senses vs. Reason #

• Man has senses because he is an animal (and all animals have senses)
• But man does not have reason because he is an animal (for then all animals would have reason)
• Rather, man has reason because he is a man
• Therefore, the soul can be the proper subject of grace because it is a human soul (rational), not because it is any soul

Important Definitions #

Species (σπεῖρα in Aristotle’s framework) #

• The form or essential nature that constitutes something as the kind of thing it is
• The human soul is one species; the animal soul another; the plant soul yet another
• A thing is prior in species when it is the cause of things being understood and existing in that species

Power (potentia; δύναμις) #

• A natural property or faculty of the soul that follows from its essential nature
• Powers include the rational intellect, will, sensation, nutrition, growth
• Powers do not constitute the species; rather, they follow from it

Property (from Porphyry) #

• An attribute that flows necessarily from a species but is not part of the species’s definition
• Example: “Having interior angles equal to two right angles” is a property of triangle
• Properties follow upon the species and are not the same as the species itself

Before (Prior) #

• Three senses relevant here:
  1. Logically before: can be understood without the posterior (the essence understood without powers)
  2. Causally before: the cause before the effect (essence before powers)
  3. Epistemologically: what is prior for us in knowledge (we know the soul through powers)

Life (vita) #

• That which moves itself
• Most knowably manifested in growth (plants) and locomotion (animals)
• These are continuous motions, matching our natural knowledge rooted in the sensible and continuous

Continuous Quantity (quantitas continua) #

• Quantity that is infinitely divisible and without discrete parts
• Includes size (magnitude) and motion (local change)
• Most directly perceived by sensation
• All our thinking begins with the continuous or what is found in the continuous

Examples & Illustrations #

The Example of the Moving Creature in the Forest #

• You step on something in a wooded path—if it moves itself when you step off, you say “Ick! It’s alive!”
• If you kick a stone and roll it, you would not say it’s alive
• The key difference: self-movement vs. external movement
• This shows how the first notion of life is self-motion

The Number Two and Its Relations #

• Two is half of four, a third of six, a fourth of eight, a fifth of ten, etc.
• One might think: “Two is half of four” gives us the reason it is two
• But this is backward: it is half of four because it is two
• All these relations follow from its being the species/number two
• Therefore, we cannot reason from properties back to the species

Understanding and Hearing as Perfect Acts #

• When you hear me, you have heard me (the act is complete in itself)
• When you understand something, you are understanding something; you have understood it
• When someone loves you, they have loved you
• These are perfect acts, not imperfect like “walking home”

Growth vs. Reproduction #

• Thomas takes growth as the plant example of life, not reproduction
• Growth is more obvious and manifest than feeding or reproduction
• As soon as a plant grows, you observe it has life; growth is the clearest continuous manifestation

The Brain Surgery Case #

• A brain surgeon stimulating parts of the brain produced sensations: “I taste chocolate,” etc.
• But the surgeon could never stimulate the brain to produce: “I just willed something” or “I just made a choice”
• When the surgeon moved the patient’s arm through stimulation, the patient said: “I didn’t do it; you did it”
• The patient understood the difference between external causation and genuine choice
• This illustrates that will/choice is not a bodily part and cannot be reduced to brain function

The Triangle and Its Properties #

• Triangle (species) is a rectilineal plane figure (higher genus)
• “Having interior angles equal to two right angles” is a property of triangle
• Being green is an accident (contingent)
• The property follows from the nature of the species and is not the same as the species itself

Questions Addressed #

Q: Is the essence of the soul the proper subject of grace, or the powers of the soul? #

A: The essence of the soul is the proper subject of grace. The powers are natural properties following upon the species; they cannot constitute the species. Since grace belongs to the soul according as it is in the species of rational nature, and powers are natural properties of that species, grace resides in the essence from which the powers flow, not in the powers themselves.

Q: Why is not every soul capable of grace if grace belongs to the soul’s essence? #

A: Because grace belongs to the soul specifically “insofar as it is of this particular species”—i.e., the human/rational soul. Animal and plant souls lack the rational nature necessary. Just as man has reason not because he is an animal (in which case all animals would have reason) but because he is a man, grace belongs to the rational soul as such.

Q: What is the first and most manifest notion of life? #

A: Self-movement. The most clearly observable forms are growth in plants and locomotion in animals, because these involve continuous quantity and motion—what is most directly knowable to us through sensation.

Q: Can we reason from a property back to determining the species? #

A: No. We reason from species to properties, not vice versa. Two is two first; therefore it is half of four. We cannot say something is two because it is half of four, because it is also a third of six, a fourth of eight, etc. The property follows from the species, not the species from the property.

Q: How do we know that reason is not a body or bodily part? #

A: Because reason has operations that transcend the body: understanding universals and engaging in “large discourse” that is not confined to any bodily part. Therefore, the being of reason cannot be entirely dependent on matter.