[OrganicH2O]

I have read that Huckel's rule only strictly applies to single ring systems, but I don't completely understand what that means.

I attached a picture of two molecules I have seen described in multiple different ways by different textbook authors, naphthalene and indole. Both could be described as aromatic because they have a large ten electron pi system, or two smaller 6 electron pi systems. Is one of these descriptions substantially more correct than the other, or are both descriptors correct? And what would be the reasoning behind that decision?

Any wise words on this topic, and/or suggestions for textbook passages to read, would be greatly appreciated.

[hollytara]

The transannular pi interactions across the bridge make Huckel not strictly applicable. 

look at Dougherty and Anslyn

or any other Physical organic book.