Thevarietiesofthesesensationsdepend, firstly, onthediversityofthenervesthemselves, and, secondly, , however, , ofwhichtwobelongtotheinternal, , theoesophagus, thefauces, andtheotherinternalpartsthataresubservienttoournaturalwants, (APPETITUSNATURALIS).Theotherinternalsense, whichembracesalltheemotions (COMMOTIONES) ofthemindorpassions, andaffections, asjoy, sadness, love, hate, andthelike, dependsuponthenerveswhichextendtotheheartandthepartsabouttheheart, andareexceedinglysmall; for, bywayofexample, whenthebloodhappenstobepureandwelltempered, sothatitdilatesintheheartmorereadilyandstronglythanusual, thissoenlargesandmovesthesmallnervesscatteredaroundtheorifices, thatthereisthenceacorrespondingmovementinthebrain, whichaffectsthemindwithacertainnaturalfeelingofjoy; andasoftenasthesesamenervesaremovedinthesameway, althoughthisisbyothercauses, theyexciteinourmindthesamefeeling (sensus, sentiment).Thus, theimaginationoftheenjoymentofagooddoesnotcontaininitselfthefeelingofjoy, butitcausestheanimalspiritstopassfromthebraintothemusclesinwhichthesenervesareinserted; andthusdilatingtheorificesoftheheart, , whenwereceivenews, themindfirstofalljudgesofit, andifthenewsbegood, itrejoiceswiththatintellectualjoy (GAUDIUMINTELLECTUALE) whichisindependentofanyemotion (COMMOTIO) ofthebody, andwhichtheStoicsdidnotdenytotheirwiseman [althoughtheysupposedhimexemptfromallpassion].Butassoonasthisjoypassesfromtheunderstandingtotheimagination, thespiritsflowfromthebraintothemusclesthatareabouttheheart, andthereexcitethemotionofthesmallnerves, bymeansofwhichanothermotioniscausedinthebrain, whichaffectsthemindwiththesensationofanimaljoy (LAETITIAANIMALIS).Onthesameprinciple, whenthebloodissothickthatitflowsbutsparinglyintotheventriclesoftheheart, andisnottheresufficientlydilated, itexcitesinthesamenervesamotionquitedifferentfromthepreceding, which, communicatedtothebrain, givestothemindthesensationofsadness, , asthefeelingsoflove, hate, fear, anger, etc., asfarastheyaremerelyaffectionsorpassionsofthemind; inotherwords, asfarastheyareconfusedthoughtswhichthemindhasnotfromitselfalone, butfromitsbeingcloselyjoinedtothebody, fromwhichitreceivesimpressions; forthereisthewidestdifferencebetweenthesepassionsandthedistinctthoughtswhichwehaveofwhatoughttobeloved, orchosen, orshunned, etc., [althoughtheseareoftenenoughfoundtogether].Thenaturalappetites, ashunger, thirst, andtheothers, arelikewisesensationsexcitedinthemindbymeansofthenervesofthestomach, fauces, andotherparts, andareentirelydifferentfromthewillwhichwehavetoeat, drink, [andtodoallthatwhichwethinkproperfortheconservationofourbody]; but, becausethiswillorappetitionalmostalwaysaccompaniesthem, theyarethereforenamedappetites.
