Is it Improper to Put a Quote in a Cover Letter?

As an employer, I would do what I just did - laugh my head off mentally. Dude, that is SO sophomoric and inappropriate I can barely describe it. You're applying at a BUSINESS. Your personal poetic love for music is completely irrelevant ! Your application would be in the trash bin within seconds after I read that BS. Stick to what classes you have taken that in any way relate to business or any customer service type things you have done.