Meditations on First Philosophy (Unabridged‪)‬

Rene Descartes, mathematician, scientist, and first "modern philosopher", wrote Meditations on First Philosophy, a six-part treatise first published in Latin in 1641, to deconstruct "belief" and, using reason and science, discuss the only things we can truly know for sure. 

Each of the six parts of this book represents six of Descartes’ meditations that occurred on six subsequent days, making it also, in no small part, an autobiographical piece of work. This text, and Descartes’ metaphysical and philosophical system as a whole, is still studied today and is considered amongst the most influential philosophical work in history.