The "unseen" is a term that refers to what is not subject to direct observation by any of the five senses.
Love is an obvious example of something important that is unseen. Intelligence is another example. Additional examples include:
- deterrence of crime by self-defense
- prayer and its effects
- remarkable migration patterns of butterflies and birds
- homing powers of fowl
- the medical harm from gambling and pornography
- Newtonian action-at-a-distance
- the invisible hand
Materialists generally deny the existence of the unseen.