This document explains how to view and hide calendars in Apple iCal (Mac OS 10.5-7) or Calendar (Mac OS 10.8-9).
In iCal/Calendar, a calendar is either visible or invisible. All calendars with view enabled are visible in the iCal/Calendar window at the same time. Color coding allows them to be distinguished one from another. iCal/Calendar will shift and shrink event blocks to show events that occur at the same time or overlap. This view/hide paradigm works for all calendar views (Day, Week, Month, Year).