XSL: transform an element only if it's a descendant of another element

I recently had to work on WordProcessingML documents and wanted to transform only those w:p elements that were within the subtree of the w:body element. My initial solution was "a bit" complex: match all w:p elements that have a w:body ancestor.

<xsl:template match="w:p[ancestor::w:body]">

There is (as always) a much more elegant solution:

<xsl:template match="w:body//w:p">