The marriage of Joseph and Mary

Super Flumina

under the patronage of St Joseph and St Dominic

By the rivers of Babylon there we sat and wept, remembering Zion;
on the poplars that grew there we hung up our harps. . . Ps 136

St Dominic


Philosophy behind this website

Professor Solomon's Introduction to Philosophy

11th September 2001


Australia's Catholic Bishops

Australian Catholic Bishops should say

Australia's Support for Legislation Worthy of Adolf Hitler


Bill of Rights




Church's Fathers & Doctors

Church's Teaching on Divorce, Contraception and Human Sexuality

Compatible sites


David Attenborough

Defamation of Catholicism

Discipline & the Child

Dismissal of the Whitlam Government

Economic Problems

Evangelium Vitae 73



Freemasonry & the Church

God is not Material

Harry Potter



Letter of St Paul to the Hebrews

Mary MacKillop

Miscellaneous Papers



Moral Issues

Non-directional Counselling

Papers written by others


Politicians & the Catholic Church

Pope Benedict XVI

Pope Leo XIII

Pope Pius XII

Popes on St Thomas



Religious Freedom

Questions for Catholic Parents in Parramatta

Research Involving Embryos Bill - Letter to the Prime Minister

Sts John Fisher & Thomas More

Science and Philosophy


Subversion of Catholic Education


Thomas Merton

Vatican II

For young readers:

Myall Lakes Adventure

© 2006 Website by Netvantage



Download this document as a PDF

One objection to the thesis I have advanced in Science and Aristotle’s Aether[1] was made in these terms:

“If aether is one of the media that transmits light as does air, water, etc., then we could just as well say that any one of them is the one cause or explanation.  There is no reason to privilege aether.  In any case aether, as Aristotle conceives it, is a body (no doubt very subtle - aetherial) not a pure quality.  I fear that you are hypostasising the qualitative potential of the medium which Aristotle says is common to air, water, aether etc.  We may not have a name for [this potency] but that does not mean we have to identify it with one of these corporeal bodies which function as media of light, heat etc.  The heat in water and air, for instance, is not due to one so that I need to say that the heat in water is because there is air in it.  The form of heat or light in the different corporeal media is not the same but similar only.  The heat of the air is not the same heat as that of the water though they are necessarily from the same source, and a likeness of it.”

Note that by “hypostasising” here, the critic means “treating as a substance what is in truth an accident”.

I think the objection is to be answered in this way.  Neither air nor water nor glass nor any other diaphanous medium can be the means of transmission of light from the sun.  But aether is.  Hence, aether is, to use the suggested term, “privileged”.  I accept that aether is a substance, though not in the sense in which we understand that term of common material being.  It can only be called a body analogically, somewhat after the fashion in which we speak of the sea as “a body of water”.  The qualitative potential in aether cannot be the same as that in air, water, or glass, etc. because aether is not a material substance in the same way as those things are, but analogically so.  Thus, in contrast with the manner in which these qualities appear in air, aether is not lit by the light it carries, nor is it heated by the heat.  Aristotle sets forth the reason why this is so in De Caelo I, 3:

“Alteration is movement in respect of quality… {Q]ualitative states and dispositions do not come into being without changes of properties.  But we see that all natural bodies which change their properties are subject without exception to increase and diminution.”

But aether is ungenerable and incorruptible, that is, not subject to increase and diminution.  Hence it is not able to be affected by the qualities it carries.  St John of the Cross demonstrates the truth that light in aether is invisible in his theological treatise, The Ascent of Mt Carmel.  When the light and heat borne in aether meet a body of common matter, as for instance, a space station in the residual atmosphere about the earth, they light up and heat that common material body.

There is a difference between light and heat.  Once it has arrived after passage through the aether from the sun, the mode of heat’s transmission changes.  This occurs in three ways, radiation, convection and conduction, each of them modes proper to the bodies in which the heat finds itself.[2]   Aristotle distinguishes heat from light precisely in this difference in mode of tranmission.  But light’s facility does not change upon its arrival via the aether at a common material body.  It remains as it was in ‘space’.  Ergo, I argue, the vehicle of its transmission remains aether.  In my view the speed of development of light is altered by the diaphanous medium in which it finds itself because the atomic structure of that (common material) body suppresses this facility of aether.  This suppression is notable in diaphanous bodies such as water and glass but hardly signifies for air.  It is measured by refractive index.  Science takes as a standard for refractive index the speed of light’s development in vacuo.  For practical purposes, however, it uses air at a standard temperature and pressure[3] .  Inevitably, then, air has a refractive index relative to that of a ‘vacuum’.  Though I cannot locate a figure, it is probably of the order of 1.0005, marking a fractional slowing of light’s development in earth’s atmosphere.

We take aether’s immensity for granted.  The light from proxima centauri (part of alpha centauri, the closest star—there are in fact three stars so closely aligned that the human eye cannot discriminate between them) travels [186,000 x 31,536,000 x 4.22] miles to reach our eyes[4] , only the last twenty of which are constituted by earth’s atmosphere.  In the whole universe no element of common material being is more extensive than is aether.

Christopher A Decaen has this to say in his paper Aristotle’s Aether and Contemporary Science:

“If aether is incorruptible two conclusions follow right away, one pertaining to its substantial principles and the other pertaining to its qualities.  First, aether's prime matter and substantial form must be so perfectly united that the latter must actualize and thereby exhaust the potency of the former, insofar as an incorruptible body by definition must lack the potential to become anything else; aether must possess a ‘certain total and universal perfection’ that thoroughly fulfills its potency for existence.  Indeed, if one were not to distinguish fulfilled and unfulfilled potencies, one might be tempted to say that the heavenly substance has no prime matter.  More accurately, however, one should conclude that, unlike sublunary composites, aether's prime matter is always perfectly fulfilled, so it is inseparable from its form, and in this sense is not really distinct from it.  Likewise, since its prime matter would not be a principle of aether's coming to be, but only of its being, it would not be the same sort of prime matter that is a principle of mundane substances (which is a principle both of coming to be and of being); it would be called prime matter only analogously.”[5]

I had early entertained doubts as to whether light was carried in aether and thought that it was simply a pure instrument of light’s transmission.  I accepted, however, in accordance with the mind of Aristotle and St Thomas, that light is a quality and aether is in potency to that quality.  Modern science can show us that it is in potency to many other qualities too, including those it characterises as “electromagnetic energy”.  It is almost as if, qua these potencies, aether is not material at all.  I think, then, that one may licitly speak of aether almost as if it was an hypostasised accident.

Aether is, in my view, the matrix of all physical reality, though by ‘matrix’ here I do not mean that it is the source of being of common matter after the fashion of a mother liquor towards the crystals that grow in it.  A fish cannot exist except in water which is a per se cause neither of its coming into existence (becoming) nor its existence (being).  Yet water is an essential condition, a cause per accidens, in respect of both.  In the same way, I contend, no material thing comes into existence, or subsists, but in aether, which is just as essential to it as is water to the fish.

What follows if this be true?  Aether must be ontologically prior (i.e., prior in the order of reality) to all common matter.[6]   Perhaps it is to be comprehended in the expression “the heavens” in the very first words of the Book of Genesis, "In the beginning God created the heavens and the earth". In which event “the earth” may be taken as signifying all common material being throughout the universe, and the order in the passage as indicating the order of their creation, first “the heavens”, then “the earth”.[7]


Michael Baker
29th June 2008—Solemnity of Sts Peter & Paul


[2]   The Principle of Reception applies—Quidquid recipitur, per modum recipientis recipitur.  (Whatever is received, is received according to the manner of the recipient.)

[4]   I find this manner of calculation more graphic than showing the calculation as 2.475 x 10 to the power of 13.  Incidentally, while we are busy gazing into the aether of the night sky, the earth is moving through it at about 15 miles per second.

[5]   Aristotle’s Aether and Contemporary Science, The Thomist, 2004, cf.  The paper was originally freely available on the internet.  One must now subscribe to the journal to obtain access.  Decaen quotes a phrase from St Thomas’s commentary on Aristotle’s De Caelo (I De Caelo VI, 6):  “huic autem materiae vel subiecto non est nata inesse alia forma, sed forma sua replet totam potentialitatem materiae, cum sit quaedam totalis et universalis perfectio.”

[6]   This distinction between the order of reality and the order of time (the ontological order and the temporal order) is critical in metaphysics.  An illustration will assist: a man is ontologically prior to his shadow, even though the two be together in time as he walks across a sunlit beach;  his foot is ontologically prior to the footprint it makes in the sand.  The sea is ontologically prior to the fish that swim in it even if Almighty God created the two at the same instant.

[7]  This article was revised on 10th February 2012 following a revision of 'Science and Aristotle's Aether'