We see everything as possessing 'an underlying reality or true nature that one cannot observe directly, and it this hidden nature that really matters'.

Whaling left few older individuals to observe directly.

Solvated electrons occur widely although they are often not observed directly.

While dark energy can not be observed directly, its basic properties can be inferred from its effect on structure formation in the universe.

Speciation has been observed directly and indirectly in the lab and in nature.