When I first saw this I thought it was a Fleischer satire of Disney’s Fantasia, but it actually came out three years before Fantasia (1940). I imagine Fantasia was already in some sort of production at that point, so it doesn’t seem unlikely it may have been a satire of the seemingly pretentious and grandiose idea of it at the time, I suppose. This came out before Snow White (1938), Pinocchio (1940), or any of the Disney Features, so the idea of a feature length cartoon probably seemed ridiculous to a lot of people at the time, let alone one that featured animation and classical music.
Another Fleischer cartoon utilizing the rotograph. They use it very well here, having the mundane “real world” scenes take place in 2d, and the 3d scenes in Dreamland. The content seems atypical for a Fleischer cartoon… a sweet & cute little story, entirely free of violence and mayhem. Adult anxieties are present as usual for Fleischer cartoons, though… in this case an apparently single mother trying to support children in total poverty (from 1936, the depths of the Great Depression).
Here’s a fun Fleischer Studios cartoon that makes great use of the Max Fleischer invention, the Rotograph… it is an early example of the technique, as the cartoon is from 1935 and the patent wasn’t filed until 1936. The Rotograph was a technique of building a miniature set on a turntable that could be rotated while shooting cels in front of it to make it appear that the 2d drawings were in a 3d space.