Hobson’s series of twenty lectures are concerned with establishing how the relation between the complex of knowledge and ideas denoted by the term Natural Science ought to relate to the other factors of human experience with which religion and philosophy are concerned. Hobson first gives a general account of what is essentially involved in the scientific outlook, surveying its methods as a means to establishing its domain. Laws and theories are used in science, and he suggests that they are a systematised continuation of the formation of common knowledge, which begins with classification. He relates a restricted methodological pragmatism to the notion of truth in science. The lectures then move from the general to the specific, examining particular branches of and theories in Natural Science and their reciprocal relations to philosophy. Traditional questions regarding determinism and efficient causation, time and space, and corpuscular theories of matter are raised in light of figures such as Hume, Descartes, Aristotle and Kant. Contemporary theories in science such as Einstein’s theory of relativity, electromagnetism, and Darwin’s theory of evolution are then examined in like fashion. His discussions lead him to the conclusion that through his delineation of Natural Science, religious and philosophical thought can be free from destructive interference, with the proviso that no religion and philosophy make no encroachment into the autonomy of Natural Science in its proper domain.