of Edinburgh, Session 1883-84. 
951 
physical geologist not only observes the form and changes of the 
earth’s crust, hut explains them by the aid of the same sciences; so 
precisely must the physical economist deal with those phenomena of 
the visible universe Avhich are specially allotted to him. From the 
present point of view we must constantly bear in mind that all 
these phenomena are alike material — that all the changes which wm 
observe, whether in the earth’s crust, in organisms, or in the inter- 
action of organisms with their environment (an inquiry within 
which indeed the economic operations of mankind are not only 
recent but comparatively small), are alike expressible in terms of 
chemistry and mechanics. Social phenomena are to be viewed 
simply with regard to the matter and energy consumed or liberated, 
and physical economics is thus the study of certain forms of matter 
in motion. 
§ 16. Particular Enunciation of the Problem — Leaving to later 
chapters those considerations of biological, psychological, sociological, 
and ethical scope, which are present or latent in almost every extant 
discussion of “material w^ealth,” and endeavouring to dispense alto- 
gether with metaphysical thought and metaphorical expression, and 
postulating simply the elementary facts of physical science, and 
more especially those of the doctrine of energy, we may enter upon 
our inquiry. What is this “wealth,” what is meant by its “pro- 
duction,” its “distribution,” its “consumption?” What are “land, 
labour, and capital ? ” What is this process of “ exchange,” and 
what is the meaning of “value? ” What are “ producers and con- 
sumers,” and so on ? 
§ 17. Qualitative Analysis . — It is convenient to begin with the 
“producers and consumers.” These indeed as organisms might at first 
sight seem only admissible when biological aspects of the subject are 
being discussed, but it has just been pointed out that the physiolo- 
gist has already in great part interpreted their functions in terms of 
pure physics, and we are thus not merely entitled, but bound to 
include them in our present survey. They come before us, how- 
ever, not in all their complex relations, afterwards to be discussed 
in the biological chapter, but simply as so many forms of mechanisms 
constructed from the matter of the earth’s crust and worked by the 
energy of the sun — as so many species of automata called Homo, 
Formica, &c. Every such automaton is of course constantly wear- 
