"At whatever level of abstraction". That's the problem, isn't it ? The line between "idea" and "expression" is hard to draw, especially in music. The best way to protect freedom of ideas is to protect freedom of expression. The best way to protect freedom of expression is to treat copyright and patent as if they were awkward-but-expedient exceptions, which should be kept subject to strict limits, to the "general rule of law" (Mr. Justice Brandeis's phrase) that all works of the mind are "as free as the air to common use" once they have been disclosed.

T.