Marking Past Days

  By default, Calendar displays past days in Month views
  identically to future days.  You can choose to display past days
  with a slash or a cross through the number by setting these
  options in the General dialog box, which you can access from
  the Options menu.

  To change this setting, display the Don't Mark Past Days
  option menu in the General dialog box and choose the desired
  setting.

  Additional topics:

  *   Customizing General Settings

  *   Choosing the Days of the Week to Appear in Bold

  *   Choosing the First Day of the Week

  *   Enabling and Disabling Week Numbers

  *   Choosing the First Week of the Year

  *   Choosing Which View Appears First

  *   Starting Calendar as Iconized or Displayed

  *   Show AM/PM

  *   Using the Live Scrolling Option

  *   Making the Day View Read Right to Left

  *   Enabling and Disabling Blank Days in the Month
      View

  *   Printing Blank Days

  *   Boxing the Current Day