Who is Maeterlinck from Concerning the Spiritual in Art and what is their importance?

Maeterlinck was a poet who depicted 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 was one of the first prophets to use the spiritual atmosphere, fear, and the absence of the guide in his artistic means. He used gloomy mountains, wind, and cries as part of a symbol to attain a certain inner tone. His main device was words that have inner sound, being part of a certain object. When an object is only heard, the object becomes dematerialized while certain vibration reaches the heart.