Démonstratives
Review the forms of the démonstrative adjective.
There are two distinct forms of démonstrative pronouns, celui, etc., used when the antécédent has been named, and ceci (cela), used when the antécédent has not been named^ is unknown, or is indefinite. For example, in Regardez cecij ceci may be a book, but ceci is used unless the word livre has been mentioned, in which case we should say Regardez celui-ci.