diff --git a/chapter03/introduction.xml b/chapter03/introduction.xml
index 05488ecbc..645686311 100644
--- a/chapter03/introduction.xml
+++ b/chapter03/introduction.xml
@@ -22,8 +22,9 @@
 
   <para>For some packages, the release tarball and the (Git or SVN)
   repository snapshot tarball for that release may be published with
-  similar file names.  A release tarball contains generated files (for
-  example, a <command>configure</command> script generated by
+  similar or even identical file names.  But the release tarball may contain
+  some files which are essential despite not stored in the repository
+  (for example, a <command>configure</command> script generated by
   <command>autoconf</command>), in addition to the contents of the
   corresponding repository snapshot.  The book uses release tarballs
   whenever possible. Using a repository snapshot instead of a release