Why does the Church include All Saints' Day (Nov. 1) in her calendar of solemn feasts?  Why does the Apostles' Creed include "the communion of saints" as one of the 12 essential articles of our faith?

What is a saint? First of all, one who knows he is a sinner.  A saint knows all the news, both the bad news of sin and the good news of salvation.  A saint is a true scientist, a true philosopher:

A saint knows the truth.  A saint is a seer, one who sees what's there.  A saint is a realist.