Endless commentaries have attempted to explain the verse “And I appeared to Avraham, to Yitzchak and to Yaakov as Kel-Shakkai, but My name YKVK I did not make known to them.", but its mystery has not yet been solved. A "simple" reading would seem to suggest that this Divine statement reveals some of God's different names, with a distinction being made between two periods: to the forefathers God revealed Himself by the name "Kel-Shakkai," but He was not known to them as YKVK. Now, on the other hand, with the time drawing close for redemption, God reveals Himself to Moshe with this latter name – as we see at the beginning of the utterance, in verse 2: "I am YKVK."
This explanation presents a great difficulty: the name YKVK (the "Tetragrammaton,") appears more than a hundred times in Sefer Bereishit, The name is used not only in the narrative, but also in the language of various speakers – including God's own utterances to both Avraham and Yaakov.
A close analysis of the text leads to the understading that there is a connection between each of these names and the nature of the promise that is associated specifically with that name. What God promised to the forefathers when He appeared to them as Kel-Shakkai – that He would multiply their seed greatly – He has already fulfilled; what remains now to be fulfilled is the other aspect of the promise to the forefathers, and the fulfillment of that aspect – the promise of the land – is the main subject of the rest of the speech.
