Patanjali was one of the founders of the yoga tradition, sometime between 200 and 400 BC (pre-dating Buddhist psychology) and a student of the Vedas. He developed the science of breath and mind and wrote his knowledge in the form of between 194 and 196 aphorisms called the Yoga Sutras of Patanjali. These remain one of the only scientific books written in poetic form. He is reputed to have used yoga therapeutically for anxiety, depression and mental disorders as common then as now.