 In the early 11th century, Avicenna theorized about the influence of emotions on health and behaviors, suggesting the need to manage emotions.Early modern views on emotion are developed in the works of philosophers such as René Descartes, Niccolò Machiavelli, Baruch Spinoza, Thomas Hobbes and David Hume.In the 19th century emotions were considered adaptive and were studied more frequently from an empiricist psychiatric perspective.