The concept of nature (phusis) is ubiquitous in Aristotleʼs work, informing his thinking in physics, metaphysics, biology, ethics, politics, and rhetoric. Much of scholarly attention has focussed on his philosophical analysis of the concept wherein he defines phusis as “a principle or cause of being changed and of remaining the same in that to which it belongs primarily, in virtue of itself and not accidentally” (Phys. 192b21-23) and the implications this has in various parts of his philosophy. It has largely (...) gone unnoticed, or unremarked, that this is not the only understanding of phusis present in his thinking. This thesis argues that in addition to his philosophical understanding of phusis, there is another, pre- theoretic understanding at work. " After unpacking this pre-theoretic understanding, which is best described as ʻthe natural world,ʼ I argue that there are three tensions stemming from this. First, the natural world is, at times, placed in opposition to the human realm, while at other times, the humans are included as part of nature. Second, nature is considered to be both a static state and a dynamic process of change depending on the context, which prompts Aristotle to claim, in different places, that ageing and dying are both natural and unnatural. Third, nature is treated both as an ideal and as something to be overcome. This thesis attempts to bring to light Aristotleʼs pre-theoretic understanding of phusis and to draw out these three tensions. In the end, I suggest that modern confusions about nature may be informed by considering how they are reflected in the work of the first great thinker about nature, Aristotle. (shrink)