I want to know the answer to the following question:
Along with Descartes, Machiavelli and Hume, what notable philosopher developed a theory of emotions?
All the background I'm provided with is that "There are also theories of emotions in the works of philosophers such as René Descartes, Niccolò Machiavelli, Baruch Spinoza and David Hume.". Is that enough to answer the question?