This book introduces us to the knowledge of the healing power of plants, particularly their active extracts: essential oils. We will discover the therapy of essences, which often have evocative names such as cypress, lavender, patchouli, and sandalwood. The method is accessible to any reader willing to observe themselves: for each symptom or disease presented, there corresponds a specific remedy. The power of essential oils is such that they can be classified as medicines. This work thus becomes a tool for self-medication, without excluding the necessity of consulting a specialist to establish a diagnosis or to understand the nature of the patient's condition.