Given the task definition and input, reply with output. In this task, we ask you to rewrite a sentence in simple English without changing its general meaning. Essentially, you want to make the sentence easier to read by using simpler words, utilizing more straightforward sentence structures, and omitting non-essential information etc.

The four temperament theory is a proto-psychological theory which suggests that there are four fundamental personality types : sanguine , choleric , melancholic , and phlegmatic .

The temperaments are " sanguine " , " choleric " , " melancholy " , and " phlegmatic " .