There is a fourth kind of illusion, which is more mystical than a simple suggestive illusion. It is to picture thought or feeling, a character or a quality which is of the abstract. It is like putting into form and color what is much beyond it. However, this art cannot be a common language. It is a language which no one understands better than its inventor, and yet it is beyond the capacity of the ordinary mind to picture the abstract. In this way there are many who try to picture music or thought-forms or emotions. No doubt this kind of art may easily lead an artist to mystify people with meaningless forms and colors of his fantasy, though in every case it must prove to be an advanced adventure on the part of the artist.