I've been working my way through A History of Political Theory, Third Edition, by George H. Sabine.
The value of this book is in its breadth, its overview of the history Western Political Theory, and the pointers to further reading. I freely admit that it is often a tertiary source, but it was a mild surprise to read the following:
It was the essence of Thomas's philosophy that it essayed a universal synthesis, an all-embracing system., the keynote of which was harmony and consilience. God and nature are large enough and opulent enough to afford a niche for all the endless diversity that makes up finite existence. The whole of human knowledge forms a single piece. Broadest in extent but least highly are the particular sciences each of which its special subject-matter; above these is philosophy, a rational discipline which seeks to formulate the universal principles of all the sciences; above reason and depending upon divine revelation is Christian theology, the consummation of the whole system. But though revelation is above reason, it is in no way contrary reason; theology completes the system of which science and philosophy form the beginning, but never destroys its continuity. Faith is the fulfillment of reason. Together they build the temple of knowledge but nowhere do they conflict or work at cross purposes.
The picture which Thomas drew of nature conformed exactly to his plan of knowledge. The universe forms a hierarchy reaching from God at the its summit down to the lowest being. Every being acts under the internal urge of its own nature, seeking the good or form of perfection natural to its kind, and finding its place in the ascending order according to its degree of perfection. The higher in all cases rules over and makes use of the lower, as God rules over the world or the sou over the body. No matter how lowly it may be no being is wholly lacking in value, for it has its station, its duties and its rights, which it contributes to the perfection of the whole. The essence of the scheme is purpose, subordination to an end. In such a structure human nature has a unique place among created beings, since man possesses not only a bodily nature, but also a rational and spiritual soul by virtue of which he is akin to God. He alone of all beings is at once body and soul, and on this fundamental facts rest the institutions and the laws by which his life is directed.
(emphasis added) [George H. Sabine, A History of Political Theory, Third Edition, pp. 248-49].