Importing XML into XSL via document() function

I understand how to use the Xpath document() function to import XML into
XSL, then accessing individual node values from that XML. That is, for
example,

<xsl:variable name="extNode" select="document('foobar.xml')/myDoc"/>
<stuff>Title is <xsl:value-of select="$extNode/head/title"/></stuff>

What I would like to do, however, is to use the entire piece of imported
xml--tags and all:

===========================
File foobar.xml:
<myDoc><x>foo</x><y>bar</y></myDoc>
===========================
File translate.xsl:
<!-- ??? -->
<xsl:variable name="extNode" select="document('foobar.xml')"/>
<stuff>Imported xml here:<xsl:??? select="$extNode"/></stuff>
===========================
Output desired:
<stuff>Imported xml here:<myDoc><x>foo</x><y>bar</y></myDoc></stuff>
===========================

What is the XSL code to accomplish this?

 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list