Maharal:
Therefore, it is appropriate that there are [specifically] four kingdoms, because they take away from the honor of G-D and He is ONE (Devarim 6:4).
E-man:
The Maharal is going to explain why the number four is appropriate to be in opposition to the number one. He is trying to explain why the four kingdoms, the entities that take away or diminish the glory of G-D in this world, are specifically enumerated as four. Also, the Maharal is pointing out why the number four is the antithesis to the number one.
Maharal:
The middle (or center) is connected to the number one because there is only one exact center.
E-man:
Rav Hartman brings down another statement from the Maharal in Netzach Yisroel in the first chapter that helps clarify this idea. "All unity is in the middle (center) because the edges are separate (many), but there is only one center."
Maharal:
Therefore, there is only one Temple and only one Jerusalem and they are in the center of the world because the center was given as a keepsake for them. So too, the Jewish people, that they are a singular (unique) nation, the land was given to them as a keepsake since it is singular (unique) because it is at the center of the world.
E-man:
The Maharal is saying that all these things are unique: The land of Israel, Jerusalem, the Temple and the Jewish people. They are all unique based on different ideas. The land of Israel is considered the center of the world (there are a million ways to explain this), Jerusalem is considered the center of Israel, and the Temple is considered the center of Jerusalem. The Jewish people are unique in a lot of ways, but suffice it to say that they are the only nation to have spoken with G-D.
Maharal:
The general idea is that anything that is singular (unique) is given, as a keepsake, the (character traits of the) center. Something that is removed from singularity (like complexity) is connected to four, this represents the four directions that travel away from the center. Therefore, there are four kingdoms (that rule in this world and diminish the glory of G-D in this world) that represent the four directions that travel away from the center.
E-man:
The Maharal is trying to explain that something that is unique in the world is connected to the number one. The number one relates to anything in the center. There is only one center of anything and that is the character trait of the number one. However, anything that is diverse (or complex), is connected to the number four, because it represents the four directions that lead away from the center. Therefore, anything that is many or diverse is connected to the number four. I know, it is confusing.
Maharal:
Therefore, we learn out from the words of תֹהוּ וָבֹהוּ (unformed and void) about the four kingdoms because this language comes to teach us about the imperfection that exists in the creation [of the world]. It is from the deficit of the creation that these four kingdoms arose. [These four kingdoms] were designated for this, that their rule would take away from [the glory of] G-D to the extent that they would nullify His singularity (uniqueness) in the world.
E-man:
Rav Hartman explains this idea so that it is more readily understandable. The imperfection in the world is that the presence of G-D is not felt and it appears to be that the world was established and exists without G-D. Meaning, the four kingdoms serve to mask the presence of G-D. They allow for man to think there is no G-D and that the world runs on its own. Or, at the very least, the four kingdoms cause people to think that G-D is not the only powerful being.
Maharal:
With the destruction of the four kingdoms the verse says (Zechariah 14:9):
ט וְהָיָה יְהוָה לְמֶלֶךְ, עַל-כָּל-הָאָרֶץ; בַּיּוֹם הַהוּא, יִהְיֶה יְהוָה אֶחָד--וּשְׁמוֹ אֶחָד. | 9 And the LORD shall be King over all the earth; in that day shall the LORD be One, and His name one. |
But, as long as these four kingdoms rule the world the glory of G-D will not be revealed in His world.
E-man:
The point here is that the four kingdoms take away from the oneness of G-D. This means that G-D can not be revealed or understood while the four kingdoms are in control of the world. They mask G-D's presence because the glory of G-D is only realized when people see that G-D is the only all powerful one. However, with the existence of the four kingdoms, it appears that either G-D does not exist, or that He is not the only all powerful one.
Maharal:
Therefore, these four kingdoms come from the imperfection that exists in creation, for it is impossible that the world should be created complete (without imperfection), rather there must be a deficit. However, this imperfection does not stem from G-D, the creator of everything, rather it comes from the fact that the world is a creation. This is alluded to in the verse (Genesis 1:1-2):
הָיְתָה תֹהוּ וָבֹהוּ, וְחֹשֶׁךְ, עַל-פְּנֵי תְהוֹם. All of this refers to the imperfection that is connected to one thing (the creation). All of these names תֹהוּ וָבֹהוּ [tell us] that the creation is not complete and they teach us about the imperfection that is inherent in the creation.
E-man:
Here the Maharal is just summing up. The point is that there is an imperfection in the world and it is hinted to in Breishis (Genesis). This imperfection does not stem from G-D, rather it comes from the mere fact that the creation is something that is created. The idea of being created means that there is an inherent imperfection in this creation. The Maharal also hints at a much deeper idea here. The idea that since something is physical it is therefore distant from G-D. The world is a physical place and therefore it is far away from G-D. This adds to the barrier between the world and G-D which leads to the ability of the four kingdoms to mask G-D's presence.