The guts of it.
Society and the English language afford 'guts' almost independent sentient being status. Long considered the source of courage, 'that took guts'; determination, 'what a gutsy effort'; and instinct or intuition, 'I had a gut feeling', the guts have also been an emotional powerhouse - disappointment is likened to 'being kicked in the guts' and an intense dislike for someone can be summed up by 'I hate your guts'.
Lee
Rachel
R
D041981:Gastrointestinal Tract; D006801:Humans; D009626:Terminology as Topic