I refer rather frequently to hylemorphism, which is the Aristotelian view that nature is made of substances comprised of form and matter. Hylemorphism was adapted by Thomas Aquinas, as well as by Maimonides and Averroes, and became the basis for much of Western metaphysics during the High Middle Ages.
Hylemorphism is a metaphysical viewpoint, not a scientific theory, per se. Like all metaphysical views, it doesn't make quantitative predictions. Rather, it is a framework for understanding nature, and it succeeds or fails in accordance with the rigor and application it provides.
The hylemorphic view of nature is basically simple, although its implications are not simple.
Nature is composed of substances. A rock is a substance. A tree is a substance. A man is a substance. A substance is an individual intelligible thing that exists.
Every substance is a composite of form and matter. Form and matter in hylemorphism are not what we moderns take these words to mean.
Matter and form are principles, not things, and they don't exist independently of substances.
Form is the intelligible principle of a substance. That is, it is the aspect of a thing that can be understood. The form of a tree is its biology, its weight, its shape, its color, etc.
Matter is the principle of individuation. It is what makes a substance a particular existing substance. The matter of a tree is the principle of the tree that makes it this or that specific tree, rather than a generic tree.
There is much more to hylemorphism, such as the nature of change, issues of teleology, the nature of the soul/mind, the existence of God, etc.
By the 16th century, particularly with the work of Descartes and his followers, hylemorphism was truncated, and eventually hylemorphism fell into disuse and even into disrepute.
"Matter" came to mean stuff with extension in space, and came to include some aspects of the hylemorphic concept of substance. The concept of form was largely cast aside, to be replaced with vague reference to laws of nature, etc. We moderns have pretty much forgotten the classical understanding of nature, although even our language retains reference to it (e.g. "information" refers to the process by which a form-- an intelligible principle-- is understood).
It has been said, with justification, that this shift in metaphysics was the most profound intellectual change in the West. We live with the consequences of the abandonment of hylemorphism today, and in fact we are so profoundly altered by the consequences of this abandonment that we have difficulty understanding it.
I believe that the hylemorphic understanding of nature was far superior to modern mechanism, both from a metaphysical standpoint and from a scientific standpoint. Hylemorphism incorporates mechanism, but provides a deeper understanding of nature. There is a movement in the philosophy of science called New Essentialism that is reexamining modern science-- especially quantum mechanics-- from the standpoint of classical hylemorphic metaphysics.
Over time I'll try to post quite a bit on this topic. It fascinates me.
(For a great introduction to hylemorphism, you can't do better than philosopher Ed Feser's blog and books. Highly recommended.)