call it a day vs preface

call it a day

• To cease the activity for the day. 

• To retire. 

preface

• An introduction, or series of preliminary remarks. 

• A title or epithet. 

• The beginning or introductory portion that comes before the main text of a document or book. 

• The prelude or introduction to the canon of the Mass. 

• To give a preface to. 

• To introduce or make a comment before (the main point).