This book provides a general framework for understanding nature to revive the philosophical study of nature as a complementary research project to the empirical exploration of nature. It demonstrates that the a priori research of nature is a viable science, by articulating its principles and demonstrating their effectiveness in explaining the most fundamental features of nature - time, space, and its laws. The original contribution of this book is twofold. Firstly, it introduces a unique method for undertaking conceptual analysis. The effectiveness of these tools is demonstrated in exploring the most general and fundamental features of nature. Secondly, it introduces a novel conception of nature - "internal relationalism" - that offers an insight into the structure of nature and its most fundamental features. Thus, it offers answers to some of the most fundamental questions that have plagued philosophers and scientists for millennia, concluding with the question "Why is there something rather than nothing?" This book is of interest to metaphysics, philosophers of science who focus on the foundations of physics, and philosophically-minded physicists, especially those whose research interests include the nature of time and space.