Most human belief systems include some stipulation or notion that we as a species are both different, and somehow preferred to whatever it may be that prefers things out there. I feel this mostly comes from the evolutionary advantage that believing you are special confers. This implies that any groups of life existing under evolutionary pressures have at least the possibility of developing whatever properties there are that make the special group special.
Thinking Galactically there's a need for a name for the entities that fit into this group, and The Advancement has used Fours as that name.
The name is significant as it pertains to four galactically significant concepts. First it is an integer, a number system understood by all Fours. Second it references the number of nucleotides in DNA, a galactically necessary building block for life. Third are the four dimensions our galaxy resides in: three spatial, and one of time. And finally four evokes the first creation of Five that Fours make--a stack.