the hidden spirit of the akeidah

The Torah tells us that a korban olah of a cow must be shechted "lifnei Hashem," but then a few pesukim later tells us that sheep must be shechted "tzafona fifnei Hashem" (1:11) Why the addition of the extra word "tzafona?"  The Midrash writes:  

When Avraham did the akeidah of Yitzchak, Hashem prepared two sheep offering [one in place of Yitzchak, one in place of the ram actually offered], one for the morning, one for the afternoon.  Why did he do this?   So that when the Jewish  people offer the korban tamid and read this parsha of “tzafona lifnei Hashem” Hashem will remember akeidas Yitzchak.  “I testify by heaven and earth that whether goy or yisrael, whether man or woman, whether eved or maid, whoever reads this parsha of ‘tzafona lifnei Hashem,’ Hashem will remember akeidas Yitzchak…”

Why is it the word “tzafona” in particular that is a reminder of the akeidah?  Sefas Emes explains that in addition to “north,” the word “tzafon” also means hidden (there are a number of explanations as to how these two meanings are related, but they all strike me as speculative).  Akeidas Yitzchak didn’t happen once and then become past history – the power of mesirus nefesh of the akeidah lives on hidden inside each one of us.  When a person brings a korban he is in fact re-enacting in a small way the akeidas Yitzchak; he should feel that he is offering his entire self to Hashem but Hashem in his mercy chooses to accept a sheep as a substitute.  The memory of the akeidah lives on through korbanos because through the korbanos we demonstrate that we embody within that spirit of the akeidah.