Eyes glazed in reverie, wilting plants, a mythological marble head - all the stuff of Symbolism is accumulated here in a painting that manifests the movement’s introspective mood. Locking the door and vanishing into imagination was what the fin de siècle was all about....
[https://www.theguardian.com/artanddesign/gallery/2017/aug/21/guggenheim-exhibition-mystical-symbolism-josephin-peladan-]
The aim of the Symbolists was to turn away from what they saw as the materialism of Impressionism. Instead, they sought to be evocative, to suggest a mood, or an abstract idea... ...we want to be able to read the painting, but so much of it is ambiguous and undecipherable. What we are left with is a mysterious and haunting image that speaks to the anti-materialist and inward-looking interests of so much art of the late 19th century.
[https://www.khanacademy.org/humanities/becoming-modern/symbolism/a/khnopff-i-lock-the-door-upon-myself-essay]