Then Ven. Ananda went to the Blessed One and on arrival, having bowed down to him, sat to one side. As he was sitting there he said to the Blessed One, "It is said that the world is empty, the world is empty, lord. In what respect is it said that the world is empty?"
"Insofar as it is empty of a self or of anything pertaining to a self: Thus it is said, Ananda, that the world is empty. And what is empty of a self or of anything pertaining to a self? The eye is empty of a self or of anything pertaining to a self. Forms... Eye-consciousness... Eye-contact is empty of a self or of anything pertaining to a self.
"The ear is empty...
"The nose is empty...
"The tongue is empty...
"The body is empty...
"The intellect is empty of a self or of anything pertaining to a self. Ideas... Intellect-consciousness... Intellect-contact is empty of a self or of anything pertaining to a self. Thus it is said that the world is empty."
See also: MN 121; MN 122; The Mind Like Fire Unbound by Thanissaro Bhikkhu, chapters 1 and 3; "No-self or Not-self?" by Thanissaro Bhikkhu; and "The Not-self Strategy" by Thanissaro Bhikkhu.