Stoicism is currently enjoying a surge of interest as a system of thought which can be applied to your life. This ancient Greco-Roman philosophy sought answers to such perennial questions as "What do I need to do to be happy?", "What is virtue?" and "How should I best make use of my life?". In this introduction, we explore Stoicism as a practical system of philosophy aiming to lead its practitioners both to moral goodness and to inner tranquillity in the face of life´s difficulties and shifting fortunes. We will show how Stoicism reconciled the idea of being inwardly free from preoccupation with external things, with a deep ethical concern for the good of others and of society. We will explore its history, main ideas and maxims, and influence of Stoic philosophy. We will look at the divisions of Stoicism in terms of cosmology and ethics. After an initial presentation of its origins in the thought of Zeno of Citium, this course dives into two of the great ancient Stoics, Epictetus and Seneca. Attentive students will emerge with a solid understanding of the fundamentals of Stoicism and its enduring relevance." This is the first part of a three-part course on Stoicism. Parts II and III will move on to discuss central figures of Roman-era Stoicism - Seneca and Marcus Aurelius.