According to halacha, when a person says the word "echad" (אחד) in Shema:
בדלי"ת צריך להאריך יותר כדי שיעור שיחשוב שהקב"ה יחיד בעולמו ומושל בד' רוחות העולם
[One should] draw out the dale more [than the Cheis] in order to think that Hashem is one in His world and he rules over the four corners of the world (Shulchan Aruch HaRav 1:61-7).
In Torah Or (נה,ב) the Alter Rebbe of Lubavitch explains that:
ובד' רוחות העולם שהם בחי' ו"ק העולם
...the 4 corners of the world which are on the level of the six directions of the world.
My question is, is there something unique about the number 4 in comparison to 6? In other words, can we learn anything from the number 4 that we would not have learned from 6?
