They bear witness to the undying vitality of Greek philosophy in its search for the ultimate entities which are the factors of the fact disclosed in sense-awareness.

This search is the origin of science.
The succession of ideas starting from the crude guesses of the early Ionian thinkers and ending in the nineteenth century ether reminds us that the scientific doctrine of matter is really a hybrid through which philosophy passed on its way to the refined Aristotelian concept of substance and to which science returned as it reacted against philosophic abstractions.

Earth, fire, and water in the Ionic philosophy and the shaped elements in the _Timaeus_ are comparable to the matter and ether of modern scientific doctrine.

But substance represents the final philosophic concept of the substratum which underlies any attribute.

Matter (in the scientific sense) is already in space and time.