Human emotions were thought to be generated in the entrails; hence the AV translation ‘bowels’ in Phil. 2: 1 etc. Modern custom speaks of the heart in a similar way. There is a literal physical usage in 2 Sam. 20: 10 and Acts 1: 18, but modern versions prefer ‘compassion’ (NRSV) or ‘warmth of affection’ for the metaphorical use.