When first learning the word “money’, I’m sure many people wondered why it isn’t countable. Actually, the origin goes way back. In the early days of Rome soldiers were given a handful of salt each day. This was later replaced by a sum of money, as transporting large amounts of salt was not very efficient. The money received was referred to as their "salt money". You can also see this in the word root “sal”. For instance, the word “salary” comes from the Latin word “salarium”, now known as salt.