According to epicurus, "there is no use in philosophy" unless it

I believe the answer is: casts out the suffering of the soul

Apicurus believe that philosophy is the knowledge that help individuals to achieve self actualization in their life. In order to know whether we really successful at this and truly know whether we're happy with our life., we need to observe the sensations between pleasures and pain within our mental condition..

answer; the parasympathetic nervous system;

semi-desert lowlands, hope this !