There are times when we must suspend our righteous indignation and admit that in an earlier, simpler age, certain activities were prevalent which nowadays would have us throwing up our hands in horror.
Berlioz' Symphonie Fantastique is an example of this; an opium-fuelled exploration into the depths of the human mind.
I'm not sure that Berlioz himself was as high as a kite when he wrote it (particularly since he hammered it out in 6 weeks), but it's central theme is an exploration of the drug-impaired mind.
The version I'm currently listening to is by the Boston Symphony Orchestra under Munch.