Called All Hallow's Eve or Ancestor Night, it is when the veil between the two worlds is most pervious.  
                Observance begins at sundown on October 31. 
                This third and last of the three pagan Autumn harvest festivals acknowledges a time of cleansing and preparation for the darkness of Winter.  It is the most important of the four "greater Sabbats."   

All to myself, I think of you.
Think of the things we used to do,
think of the things we used to say,
think of each happy yesterday.
Sometimes I sigh, and sometimes I smile;
but I keep each olden, golden while
All to my self.
 Wilbur Dick Nesbit ~
American.  1871-1927