This work was originally titled The Metaphysical Foundations of Modern Physical Science in 1924, excising the word "physical" from subsequent editions. Popular information leads us to think that the work was derived from the author's PhD thesis. So far, no one else denies this.
Metaphysics. A current AI definition: "Metaphysics is the study of the most general features of reality, including existence, objects and their properties, possibility and necessity, space and time, change, causation, and the relation between matter and mind. It is one of the oldest branches of philosophy."
It was a much-maligned field of endeavor as it "intruded" upon the mechanistic aspects of science (teleology, thin hypothesizing, empiricism, experiments etc.) well before Dr. Burtt's birth in Massachusetts in 1892. But the good doctor shows in his treatise that, if anything, what we construe as modern science may've intruded on metaphysics.
Burtt, trained in theology as well as either history or philosophy (later in his career he became the prestigious Susan Linn Sage Professor of Philosophy at Cornell) had a reason for removing "physical" from the title. The problems he acknowledged in a 1931 re-write of this book's conclusion moved the problem he outlined, out of what he covered in the physical sciences, over to that of "the" sciences, generally. His original introduction showed it clearly, and he re-emphasized it in 1931: to paraphrase without going too far off course, that early medieval science notions, presuppositions, any details, needed to be collected or re-collected and collated into better understandable wholes not only to recreate the "thick, fat textuality" of metaphysics from then - but, then, to use this to prepare the ground for new cosmogonies (physical sciences) and for new appreciations of the so-called "soft" sciences. The latter, due to his inability here to define it, will have to settle for this: that the "soft" ones are really the "hard" ones. This is due to his explicating the mathematical takeover of the sciences to the detriment of scientific advance; namely, the qualitative insights "soft" sciences contain will feed the "hard" ones. Math like music is too thin and feeds off itself. He wrote this before WWII and the realization that we've gone too far in the physical/mathematical side - as atomic weapons demonstrated.
The good news is that this has been done, post WWII (e.g., Astronomies and Cultures in Early Medieval Europe by McCluskey; also the works of Karl Popper in defining actual science and protecting it, so to speak, from classicist "post modern scientism" epistemologists: the latter is on par with restorations such as by McCluskey). But there is, naturally, little utility (as in, functional, science) to have armies of science historians rolling tons of metaphysical thickness without any immediate use for it. This goes against the accidental deistic revolution Newton created, wherein (according to his mostly-German explainers, like the deist, Kant, and Liebnitz and Hegel) you need only "thinness of thought" (there comes math and statistics!) to proceed clearly to "do" science. No: you don't. These non-intuitive worshippers of Newton's Principia forgot his intuition-aimed Opticks. In their typical fashion of excising "the unimportant," there the Opticks went (trash can). Elitists ignore the tinkering of non elites. Tell that to Franklin: he read the Opticks to develop the current through which light would eventually be created for the lamps the classicists would later use to critique his invention with. (But, ack! That is mere utility!)
These are the main themes of the book. There are armies of "secondary laborers" in the science fields, unlike that of the "genius level." This is explained by the himself-ingenious, one time Avalon Professor in the History of Science at Yale, Derek J. de Solla Price. If we could but get Big Science to march in the direction Price describes to actually carry out the prescient Burtt's aims for reconstructing early metaphysical strides, there would be no need for immediate utility. It would be available, though. This was proven by Big Science using CO2 fears to motivate and fund whole armies of atmospheric scientists to keep repeating the message of immanent death from it, for years. If the shoe fits for the one, it will for the other.
As you go through Copernicus, Kepler, Galileo, Descartes, Gilbert, Boyle and Newton, you see in Burtt's work the missing areas of the theistic natural philosophers leading to the perhaps inevitable break with a supporting God (that in parting shots, Newton referred to either as "Lord God," or "a Force" in his second preface to the Principia) powering science from its "thick, fat textuality" out of the St. Augustines and contemplative Patristic Fathers, into the "thinness" of the post-Newtonian workers in science: those who've eschewed contemplation and revelation from their work in order to keep seeking revelation via math and statistics (only).
In other works Dr. Burtt pointed to a schism in western philosophy, and the one (classical philosophy: Kant, Wittgenstein, Mannheim) vs. the other (post-Roman period philosophy: Descartes, Spinoza, Berkeley; the Millses. Popper). The former side with nonintuitive rationalization of all physical phenomena; the latter are skeptical of this and seek a mend with a more theistic approach wedded to nonintuitive teleology/math proofs as they relate to science - which is observation and study of physical phenomena in (Newton's) piecemeal fashion joined with other observation where it fits.
Above all this - and Burtt is loath to enter the domain, but underlines it all over the place in what's unseen as you read - is an ancient Judaic understanding that, unlike Kant, realizes there is no such thing as a rational god in a Kantian sense - which led to the transcendentalists and probably "religious revivals" across the planet in the mid 1800s. Rather, Burtt suggests that, like the theists once did, we accept that there is such a thing as a supra-rational god SO rational, that we cannot delineate His (Her's!) rationality. In his sections on Boyle, read of this intently to see a demonstration of theism in science at its once best: the Laws of Gravity and Boyle's Law are human laws, not God's, since we, the imperfect, discovered them from an infinitude of possibilities amid a probable perfection not allowed us (yet). In this there is great room for insight and revelation. For often, it seems, "strides in science" are preceded by flashes of a kind of "light" called insight.