Dr.Tylor's theory of animism, then, as set forth in his great work, _Primitive Culture_, is that "the belief in spiritual beings" will do as a definition of religion taken at its least; which for him means the same thing as taken at its earliest.

Now what is a "spiritual being"?
Clearly everything turns on that.

Dr.Tylor's general treatment of the subject seems to lay most of the emphasis on the phantasm.

A phantasm (as the etymology of the word shows) is essentially an appearance.

In a dream or hallucination one sees figures, more or less dim, but still having "vaporous materiality." So, too, the shadow is something without body that one can see; though the breath, except on a frosty day, shows its subtle but yet sensible nature rather by being felt than by being seen.