It is held forty days after Easter, or ten days before Whitsunday, in celebration of Christ's ascension into heaven forty days after the resurrection.

It is held forty days after Easter, or ten days before Whitsunday, in celebration of Christ's ascension into heaven forty days after the resurrection.

It always falls on a Thursday, and the day is known as Ascension Day, or Holy Thursday.

the Ascension of Isaiah supply much information on this subject.

In the Ascension of Isaiah (1st century A.D.) Seth is seen in heaven.