I am of the mind that there are very few things that are not based upon reality, since we, as humans, really don't have much capacity to imagine things that have actually never existed.

For example, Pegasus, the flying horse. People knew of horses, and people knew of birds. They then merge two knowns into a new mythical being.

Having said that, it is important to not reverse the process and say that the fact that people have a myth of a flying horse means flying horses must have existed. I would only caution against that when studying these kinds of phenomena.

Anthony

You can lead a horse to water but you can't make him think.