As an illustration of the developing of a World Theory following Root Metaphor Theory (and not necessarily an exemplar, Stephen C. Pepper traces the history of thought in the Milesian School in World Hypotheses: A Study in Evidence (1942), Chapter V: Root Metaphors, §3.
Pepper begins with [Thales of Miletus (c. 620 B.C.E.—c. 546 B.C.E.)](https://iep.utm.edu/thales/) the founder of the Milesian School, who was later reported by Aristotle saying that nature of the world was a single material substance, water.
> Thales, wondering about the world, and dissatisfied with the explanations of mythology, suggested, "All things are water." He picked out a range of common-sense fact, water, which impressed him, a citizen of a seaport town, as likely to possess the secret of all things. Water stretches far and wide. It evaporates, generating fogs, and mists, and clouds, and these in turn condense in dampness and rain. Life springs out of its slime and mud, and the absence of water is death. [p. 92]
Around the same time, [Anaximander (c. 610—546 B.C.E.)](https://iep.utm.edu/anaximander/) refined that world theory with a speculation of the boundless.
> Anaximander followed Thales and thought the selection of common water rather crude. The substance of all things, metaphysical water, was not after all just common water. It was common water plus all its phases and acquired qualities. He accordingly emphasized the extensive category of infinity and a category of qualitative change which he called "shaking out." He gave the substance of all things the name _apeiron_ or "infinite." In the "infinite" lay the "mixture" of all qualities: hardnesses, softnesses, shapes, colors, tastes, and odors. For any particular object in the world, such as a ship, a leaf, a pebble, or a fire, some of these qualities were "shaken out" of the "infinite mixture" as perhaps rain is shaken out of heavy clouds. These segregated qualities then congregated in the familiar forms we perceive. [p. 92]
Slightly later, [Anaximenes (d. 528 B.C.E.)](https://iep.utm.edu/anaximenes/) extended water and boundlessness, to refine categories.
> After Anaximander came Anaximenes, who felt that Anaximander was very near to substituting an abstraction for the concrete substance of things, but apparently agreed that water did not connote the infinity which a world substance should have. He accordingly suggested air, denoting by this something more akin to what we should now call mist, which was, after all, one of the phases of Thales' "water." Anaximenes also added the clear discrimination of a category of quantitative change, namely, rarefaction-condensation, which seems to have been assumed by Thales and perhaps by Anaximander, but was not defined. It amounts to a category of the phases of matter: solid, liquid, and gas. [p. 93]
The Root Metaphor of water is induced by a World Theory, i.e. "generating-substance theory". The theory is associated with categories.
> The root metaphor of this theory thus ultimately turns out to be the characteristics of a basic material out of which all the facts of the universe can be generated by certain processes of change. The set of categories may be listed as > * (1) a generating substance (or maybe several), > * (2) principles of change like "shaking out," and rarefaction-condensation, and > * (3) generated substances produced by (1) through (2). > We might call this the "generating-substance theory." [p, 98, editorial paragraphing added]
Pepper criticizes this "generating-substance theory" on the sufficiency of Scope and Precision, as inadequate in _scope_.
> It is not a very adequate theory, though its shadow falls upon the works of many men who developed much more adequate theories. > * It is periodically revived in practically pure form, but always by men of relatively small caliber. It was revived by Bernadino Telesio in the sixteenth century and by Büchner, Haeckel, and Herbert Spencer in the nineteenth. > The trouble with the theory is that it lacks scope. There are too many facts that cannot be satisfactorily described in terms of these categories. [pp. 93-94, editorial paragraphing added]
> When attempts are made to develop these categories further so as to render them more adequate and give them the acope required of a world theory, we discover either that they break down or that they break out into various types of cognitive fallacy, or that new sets of categories are in the making and men are seeking inspiration from new groups of common-sense facts, seeking new root metaphors. [p. 94]
Philosophically speaking, the question is whether to continue with the root metaphor, or to work towards a new one. Towards modern science, the [Encyclopedia of Human Thermodynamics](https://www.eoht.info/page/Encyclopedia%20of%20Human%20Thermodynamics) thinks [Ludwig Buchner](https://www.eoht.info/page/Ludwig%20Buchner) (1824-1899), [Ernst Haeckel](https://www.eoht.info/page/Ernst%20Haeckel) (1834-1919) and [Herbert Spencer](https://www.eoht.info/page/Herbert%20Spencer) (1820-1903) were rather significant. Perhaps there were satisifed to not pursue a full World Theory, but instead a less-ambitious scope.
Pepper continues with more history of philosophy to show the reifying of root metaphor and categories, through [Empedocles (c. 492—432 B.C.E.)](https://iep.utm.edu/empedocles/), [Anaxagoras (c.500—428 B.C.E.)](https://iep.utm.edu/anaxagoras/), [Parmenides of Elea (Late 6th cn.—Mid 5th cn. B.C.E.)](https://iep.utm.edu/parmenid/) and [Zeno of Elea (c. 490-430 B.C.E)](https://iep.utm.edu/zenos-paradoxes/#H1).
> So, after Anaximenes came Empedocles, who proposed in his perplexity over the inadequacies of water, apeiron, and air a plurality of generating substances and some new principles of change; and, > * in the same perplexity, but following another path, Anaxagoras; and > * also Parmenides and Zeno, who boldly but not so wisely proposed to solve the difficulties by believing only in elemental substance, denying generating change; and > * Heracleitus, who equally boldly and unwisely proposed believing only in generating change and apparently denying permanent substance. > So we see how a world theory beginning promisingly with a root metaphor fresh from vital common sense > * grows for a while, > * meets obstacles in fact, > * is incapable of overcoming these obstacles, > * desperately juggles its categories, > * forgets the facts in the juggling of the categories, > * till these presently become so empty that some men can cast half of them overboard, devoutly believe the other half, substitute concepts for the facts, and deem it unnecessary to look back upon the forgotten facts. > When an inadequate theory reaches such a state of intellectual chaos, there is stimulus for criticism and for new insight. [pp. 94-95, editorial paragraphing added]
This 1942 writing on the scientific progress in world theories ties can be associated with a relationship between Stephen C. Pepper and Thomas Kuhn, in a foreshadowing of the publishing of [_The Structure of Scientific Revolutions_](https://press.uchicago.edu/ucp/books/book/chicago/S/bo13179781.html) in 1972.