"This passage is making a metaphysical critique of reductionism, specifically the reduction of substance to quantitative or measurable structures...The: The “Greek perversion” The author identifies a fundamental error in Greek philosophy: treating the nature of a substance as something that can ultimately be captured quantitatively by the human intellect": The Greek perversion has as its root cause one fundamental metaphysical error: belief that the nature of substance is quantifiable by the human mind. It was the genius of Aristotle and St. Thomas to see that this is not the case. But such a conclusion should not have taken genius. It is really a matter of common sense. The notion, for instance, that the marvelous substance which we call water could in any way be equated with, or reduced to, a particular atomic structure is absolutely absurd. There is simply no reasonable way that the human mind can equate electrons, spinning at comparatively immense distances around protons and neutrons, with what it knows as the substance water.

This passage is making a metaphysical critique of reductionism, specifically the reduction of substance to quantitative or measurable structures.

The central argument can be reconstructed like this:

1. The “Greek perversion”
   The author identifies a fundamental error in Greek philosophy: treating the nature of a substance as something that can ultimately be captured quantitatively by the human intellect.
2. Aristotle and Aquinas reject that reduction
   On an Aristotelian-Thomistic account, what a thing is—its substantial nature—is not identical with a measurement, mathematical description, or collection of measurable parts. Quantitative properties belong to a substance, but they don't exhaust what the substance is.

3. Water illustrates the distinction
   Saying that water is H₂O is scientifically useful, but the author is challenging the inference:

   water = a particular arrangement of subatomic particles.

   The distinction is between describing the material constitution of something and giving a complete account of what the thing is.

4. The epistemological point
   The passage argues that the intellect encounters water as water—a unified sensible substance with characteristic powers and behavior. It does not experience “water” merely as electrons, protons, and neutrons.

   Thus, even an exhaustive physical description of its constituents would not necessarily be identical to the intelligible concept of the substance.

The important qualification

There is a problem, however, with the passage's scientific formulation.

Modern chemistry does not say that water is literally reducible to electrons spinning around protons and neutrons. And the modern atomic picture isn't accurately described that way. More importantly, H₂O does not mean that water is nothing but three isolated particles; it specifies a molecular composition and bonding structure.

So the strongest Thomistic argument isn't:

“Physics says water consists of atoms, therefore physics is absurd.”

It is rather:

A quantitative account of a thing's material composition is not necessarily an exhaustive metaphysical account of the thing itself.

That is a much more defensible claim.

Where Aristotle and Aquinas enter

The key Aristotelian distinction is between matter and form. A substance isn't simply a heap of material components. Its form is the principle by which the matter constitutes this kind of thing.

Consequently, there are different questions:

• What is it materially composed of?
• What quantitative properties does it have?
• What structure does it possess?
• What kind of thing is it?
• What powers and operations belong to it because it is that kind of thing?

The first three are particularly amenable to mathematical science. The latter questions are metaphysical.

This is why the passage fits very closely with the broader Aristotelian-Thomistic objection to reductionism: the explanation of a thing's components is not automatically an explanation of the thing as a substance.

One could therefore sharpen the author's thesis considerably:

The mistake is not quantifying substances; science legitimately quantifies substances. The mistake is supposing that whatever can be quantitatively described therefore constitutes the complete intelligible reality of the substance.

That formulation gets much closer to the actual Aristotelian-Thomistic positi