Add mention of lexical scoping in Variables and Scoping

doc/manual/variables-and-scoping.rst

@@ -34,8 +34,47 @@ Notably missing from this list are
 Certain constructs introduce new variables into the current innermost
 scope. When a variable is introduced into a scope, it is also inherited
 by all inner scopes unless one of those inner scopes explicitly
-overrides it. These constructs which introduce new variables into the
-current scope are as follows:
+overrides it.
+
+Though, regarding the special case of functions, please note that Julia
+uses `lexical scoping <https://en.wikipedia.org/wiki/Scope_%28computer_science%29#Lexical_scoping_vs._dynamic_scoping>`_,
+meaning that a function's scope does not inherit from its caller's
+scope, but from the scope in which the function was defined. Thus,
+functions do not have access to variables introduced in their caller
+function's scope. For example, in the following code ``x`` is found
+in the global scope (and if no global variable ``x`` existed, an
+undefined variable error would be raised)::
+
+ function foo()
+ x
+ end
+
+ function bar()
+ x = 1
+ foo()
+ end
+
+ x = 2
+
+ julia> foo()
+ 2
+
+On the other hand, in the following example, the closure ``foo`` is
+defined inside ``bar``, therefore it inherits from its scope::
+
+ function bar()
+ foo = () -> x
+ x = 1
+ foo()
+ end
+
+ x = 2
+
+ julia> bar()
+ 1
+
+These constructs which introduce new variables into the current scope
+are as follows:
 
 - A declaration ``local x`` or ``const x`` introduces a new local variable.
 - A declaration ``global x`` makes ``x`` in the current scope and inner