▁The ▁General ▁Theory ▁of ▁Emp loyment , ▁Interest ▁and ▁M oney ▁to ▁describe ▁the ▁instinct s , ▁pro cl iv ities ▁and ▁emot ions ▁that ▁ost ens ibly ▁influence ▁and ▁guide ▁human ▁behavior , ▁and ▁which ▁can ▁be ▁measured ▁in ▁terms ▁of , ▁for ▁example , ▁consumer ▁confidence . ▁It ▁has ▁since ▁been ▁argued ▁that ▁trust ▁is ▁also ▁included ▁in ▁or ▁produced ▁by ▁" an imal ▁spirits ". ▁ ▁Use ▁by ▁Ke yn es ▁ ▁The ▁original ▁passage ▁by ▁Ke yn es ▁reads : ▁ ▁Ear lier ▁uses ▁ ▁Philosoph y ▁and ▁social ▁science ▁ ▁The ▁first ▁use ▁of ▁the ▁notion ▁animal ▁spirits ▁is ▁described ▁by ▁Des cart es , ▁Newton ▁and ▁other ▁scient ists ▁on ▁how ▁the ▁notion ▁for ▁the ▁vital ity ▁of ▁the ▁body ▁is ▁used . ▁ ▁These ▁animal ▁spirits ▁are ▁of ▁an ▁ æ there al ▁nature . ▁In ▁one ▁of ▁his ▁letters ▁about ▁light , ▁Newton ▁wrote ▁that ▁the ▁animated ▁spirits ▁very ▁easily ▁live ▁in ▁" the ▁brain , ▁n erves , ▁and ▁mus cles , ▁may ▁become ▁a ▁convenient ▁vessel ▁to ▁hold ▁so ▁sub til ▁a ▁spirit ." ▁The ▁spirit ▁Newton ▁is ▁talking ▁about ▁here ▁are ▁the ▁animated ▁spirits ▁that ▁have ▁an ▁eth ere al ▁nature . ▁It ▁rel ates ▁to ▁life ▁in ▁the ▁body . ▁Later ▁it ▁became ▁a ▁concept ▁that ▁acquired ▁a ▁psych ological ▁content ▁but ▁was ▁always ▁thought ▁of ▁in ▁connection ▁with ▁the ▁life ▁processes ▁of ▁the ▁body . ▁Therefore , ▁retained ▁a ▁lower ▁overall ▁animal ▁status . ▁ ▁William ▁Saf ire ▁expl ored