Let me explain first about the concept of myth from Hindu perspective, which is the subject matter of heated, but lively debate between two commenters above (Rickross and Dr.Vinit Aggarwal). In the West the concept of myth emerged in the context of the stories about their gods whose origin they don't know even now. That's why their myth contains the element of fiction. With this perspective, mordern historians, particularly marxists view our scriptures including RigVeda as a collection of myths: our great historical river Sarasvati was for them a mythical river until science proved otherwise. Our concept of myth or storey telling emerged and continued as a need to preserve our history, names and deeds of our great ancestors- gods, sages and kings. Our ancestors were so conscious of preserving history that they placed the names of great ancestors on natural objects like stars etc and natural phenomena most poetically expressed in term " Indra dhanush". But we can not be misled by later interpretation that Indra was an extra-territorial god as Rigveda tells us explicitly that he was our ancestor and existed on this earth in flesh and bones once upon a time. Similarly Rama, Krishna, Arjuna and all others are our ancestors of later age, not because of the religious fervour given to them by later Hinduism, but because they were kings of the clans continuing from RigVedic period of ancient Hinduism. We shouldn't judge or perceive ancient Hinduism from the parameter set by later Hinduism. For example Indra/Vishnu should not be judged by what is written about them in Purana or other scriptures .Only then we will be able to see that the story of Greek god Zeus the thunder bolt bearer is a myth of our historical figure Indra the Vajra holder. Thus our concept of myth is a story of history looking like a fiction.
Now examine the myth of witches in RV.1.133 (1-7)