Describe symbolism in Concerning the Spiritual in Art by Wassily Kandinsky

Kandinsky notes that Maeterlinck is a poet that uses fantastic and transcendental worlds, such as in "La Princess Maleine", "Les Sept Princesses", and "Les Aveugles", that are souls trying to find their way in fog while being threatened by certain forces that are both invisible and somber. He is one of the first prophets that uses the spiritual atmosphere, fear, and the absence of the guide in his artistic means. He uses gloomy mountains, wind, and cries as part of a symbol to attain a certain inner tone.