Fifty is also half of 100, which has a similar meaning; the Writings tell us that when used together with 100, fifty represents an intermediate state. God rested on the seventh day of creation. That represents a state of holiness and tranquility that was preserved in the form of the sabbath. Holier still was the seventh sabbath, which happened every 49 days. The Israelites would follow that solemn day with the “feast of the seven sabbaths” on the 50th day, and for similar reasons had a jubilee year every 50th year. For these reasons, among others, “fifty” in the Bible is the completion of a cycle, and in most cases represents fullness or sufficiency.

The number "four" in the Bible represents things being linked together or joined. This is partly because four is two times two, and two represents the ultimate linking between our desire to be good and our understanding of truth. We can also see this in the fact that most buildings are rectangular, with the four sides linking together to make a whole. We also divide directions into four -- north, east, south and west -- and talk about the "four corners" of something meaning all of it. So our special thinking naturally looks at four sides as linking together into a whole.

(Odkazy: Apocalypse Explained 417; Arcana Coelestia 1686, 9103, 9601, 9767, 9864)