Mathematics
Gr.: μαθηματικός (mathematikós) meaning "fond of learning"

is often defined as the study of quantity, structure, change, and space.

...it is the investigation of objects or concepts that exist independently of our reasoning about them.
(Mathematical realism, or Platonism)

Many working mathematicians are mathematical realists; they see themselves as discoverers. Examples are Paul Erdős and Kurt Gödel. Psychological reasons have been given for this preference -
it appears to be very hard to preoccupy oneself over long periods of time with the investigation of an entity in whose existence one doesn't firmly believe

Philosphy of Mathematics