-As an aside, although it is an important one, note that because
-the values of
-@code{font-shape} are symbols they must be introduced with a
-single apostrophe, @code{'}. That is why apostrophes
-are needed before @code{thickness} in the earlier example
-and @code{font-shape}. These are both symbols too.
-Symbols are special names which are known internally to
-LilyPond. Some of them are the names of properties,
-like @code{thickness} or @code{font-shape}, others are in
-effect special values that can be given to properties, like
-@code{italic}. Note the distinction from arbitrary
-text strings, which would appear as @code{"a text string"}.
+As an aside, although it is an important one, note that because the
+values of @code{font-shape} are symbols they must be introduced with a
+single apostrophe, @code{'}. That is why apostrophes are needed
+before @code{thickness} in the earlier example and @code{font-shape}.
+These are both symbols too. Symbols are then read internally by
+LilyPond. Some of them are the names of properties, like
+@code{thickness} or @code{font-shape}, others are used as values that
+can be given to properties, like @code{italic}. Note the distinction
+from arbitrary text strings, which would appear as @code{"a text
+string"}; for more details about symbols and strings, see @ref{Scheme
+tutorial}.