This book looks at the epistemological views and arguments of the early Stoics, in particular those of Chrysippus (3rd century BC), the third head of the Stoic school. It discusses such issues as the manner in which we perceive things and come to have notions of them, the reliability of arguments, the nature and variety of cognitive errors, and the possibility and nature of knowledge. Unlike most recent works on the subject, the aim of this book is to give a comprehensive account of Stoic epistemology as a whole as it was developed by Chrysippus. The emphasis lies - more than usual - on how the epistemological views of the Stoics are interrelated, not only among themselves, but also with views belonging to their physics and logic. The author focuses on the ancient sources and does not attempt to cover all the subjects that are discussed in the scholarly literature, but in working with the sources, he makes extensive use of the latest scholarship on the subject. Our evidence for early Stoicism is quite poor. There are probably many views and arguments we will never get to know about. But we do find lots of passages bearing on various issues in Stoic epistemology in Sextus, Galen, Plutarch, Cicero, and a few others authors. Much of Lokke's work therefore consists of putting together bits and pieces of evidence from these authors so as to try and make sense of the subjects that we know the early Stoics discussed, some of which are listed above.