Ji Kang’s “An Essay on Nourishing Life” has, for much of its history, been overshadowed by his more famous work “Sound is without Grief or Joy.” Be that as it may, “An Essay on Nourishing Life” is also an important text in that it delves into the interdependence of the heart-mind, spirit, and vital breath, and into how harmony between them is the key to ensuring physical longevity. In addition to investigating this aspect of his thought, this paper will also discuss Ji Kang’s attention to the vicissitudes of knowledge and desire and to the need to temper them with tranquility and stillness. “An Essay on Nourishing Life” can thus be read as an extension of classical Daoist theories of self-cultivation while at the same time elaborating upon them by bringing together their disparate components into a coherently unified doctrine.