Stoicism is a philosophy that has been evolving since its inception over two thousand years ago. The philosophy has undergone many changes and adaptations over time, reflecting the influence of various thinkers and cultural movements. 

During its early years, Stoicism was primarily concerned with ethics and how to live a good life. The early Stoics, such as Zeno of Citium, emphasized the importance of developing virtues such as wisdom, courage, self-control, and justice, which would enable individuals to live a life of happiness and fulfillment. The Stoics saw the world as being governed by rational principles, and believed that the key to happiness was to live in accordance with those principles.

Over time, the philosophy of Stoicism became more complex and nuanced. The Roman Stoics, such as Seneca, Epictetus, and Marcus Aurelius, emphasized the importance of inner calm and self-discipline in the face of adversity. They believed that individuals should strive to be indifferent to external events, and focus instead on developing inner strength and resilience.

In the Middle Ages, Stoicism experienced a decline in popularity, as the philosophy became associated with paganism and was largely forgotten. However, during the Renaissance, the humanist movement emphasized the importance of reason and individualism, and Stoicism experienced a resurgence in popularity. The ideas of the Stoics, such as the importance of inner calm and self-discipline, influenced many Renaissance thinkers, including Erasmus and Montaigne.

During the Enlightenment, Stoicism once again fell out of favor, as the focus of philosophy shifted to the importance of reason and empirical observation. However, in the 20th century, Stoicism experienced a revival, as people began to turn to the philosophy as a way of coping with the challenges of modern life. Today, many people see Stoicism as a practical philosophy that can help them find meaning and purpose in their lives.

The modern revival of Stoicism has been characterized by a renewed emphasis on the practical application of the philosophy. Many modern writers, such as Ryan Holiday and William B. Irvine, have written books on Stoicism that emphasize the importance of using Stoic principles to navigate the challenges of modern life. These writers have focused on the Stoic practices of mindfulness, self-discipline, and acceptance, and have adapted these practices to modern contexts.

In conclusion, Stoicism has evolved significantly over time, reflecting the influence of various cultural movements and thinkers. From its early days in ancient Greece to its current popularity in modern times, Stoicism has continued to shape the way people approach life and the world around them. While the philosophy has undergone many changes over the centuries, its core principles of self-discipline, mindfulness, and acceptance have remained constant, making it a powerful tool for those seeking to live a life of purpose and meaning.