Unexpected Context Node at Points in XPath Expression

Unexpected to me, at least.

I've been familiarizing myself with XPath for a project by browsing
around the Internet with the Firefox extension XPath Checker.

On this page:

http://en.wikiquote.org/wiki/A.I.

... I tried the following:

id('bodyContent')/h2/following-sibling::*[position()<count(following-sibling::p[1]/preceding-sibling::*)
- count(preceding-sibling::*)]

... which I expected to select the 7 ul elements following the
specified h2. The next query DOES do that:

id('bodyContent')/h2[1]/following-sibling::*[position()<count(id('bodyContent')/h2[1]/following-sibling::p[1]/preceding-sibling::*)
- count(id('bodyContent')/h2[1]/preceding-sibling::*)]

The stuff I had to add in I had expected was already present as the
context node. Why was I wrong?

- mt