Natural because they a) arise easily or spontaneously, b) are based on features existing in nature, or c) “are neither flat nor sharp.”  Timothy tends to trend towards nature and the spontaneous; Alan is more musical and organizational.

MUSING

noun (usually musings):  A period of reflection or thought.
“his musings were interrupted by the sound of the telephone”

adjective: Characterized by reflection or deep thought.
“the engaged musing gaze”