Gurl, you should see the original drawings of this painting.
Basically, Schwabe illustrated Baudelaire’s Fleurs du Mal, including this image to go with a poem that, by the way, in no way mentions mermaids or angels or anything like that (Symbolism, motherfuckers).
He then, almost ten years later, redid the image as the painting seen above above, and note the differences. Paintings were made to make money, whereas illustrations were made more often than not for entertainment purposes (pornography, for example), or satirical purposes (political cartoons, etc). This is mostly because making a painting is fucking expensive, whereas doing a drawing or a print was much cheaper. People could get away with a lot more in illustration due to the believed entertainment factor (therefor not being taken seriously), than in a painting (which would be subject to academic criticism and market value). The illustration is, in short form, purely Symbolist, utilizing fear and sex to portray a sublime and passionate idea, the idea of spleen vs the ideal in Baudelaire’s poem, and in this case the sexual activity is between a grotesque female and a female angel. What’s more, one of the parties is a grotesque monster but the female angel is in a state of ecstasy (or at least is not CLEARLY in a state of terror)
Go to the painting then, and the angel is not only now male, but the sexuality has been up played (look at that penis there), the grotesqueness downplayed, and terror up-played. Eve the serpent is now dragging the male angel down into the depths, which was not what was happening before.
The painting is a thousand times more moralizing than the illustration, because thems the breaks, and sexy, pretty, moralizing paintings still made way more money in 1907 than Symbolist passion pieces about monsters, lesbians and the love of losing control to decadence.
Also go read the poem, it’s fucking awesome.