diff -u b/core/includes/theme.inc b/core/includes/theme.inc
--- b/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -634,17 +634,17 @@
 }
 
 /**
- * Returns either the path to the current active theme or during a rendering
- * process the path to the theme or module that registered the theme function or
- * template by implementing HOOK_theme().
+ * Returns the path to a theme or to a module implementing hook_theme().
+ *
+ * The path points either to the current active theme or during a rendering
+ * process the path points to the theme or module that registered the theme
+ * function or template by implementing hook_theme().
  *
  * During rendering, elements in the render array tree are eventually passed to
  * the internal _theme() function, which decides which theme function or
- * template to use to render the element. In this context the return value of
- * path_to_theme() will be the directory path of the theme or module, that
- * exposed the information about the particular theme hook to be used for
- * rendering via HOOK_theme(). This information will be retrieved by the
- * _theme() function from the theme registry.
+ * template to use. In this context, the return value of path_to_theme() will be
+ * the directory path of the theme or module that did register this particular
+ * theme hook.
  *
  * @return string
  *   A directory path relative to the Drupal root directory.