He built there an altar to Hashem Who appeared to him.
Meshech Chochmah: What can “appeared” mean, when we speak of G-d Who has no form? Although we cannot imagine what it is like be “spoken” to by Hashem, we don’t find the notion of Divine speech as much of a challenge. We understand that Hashem’s “speech” is unlike ours, that He does not engage in any human activities. But we at least can relate to the message that is received. We can’t do the same in regard to “seeing” Hashem, because we can’t imagine how any imagery is appropriate to Him at all!
A verse in Iyov deepens the problem. “From my flesh I behold my G-d.” I will posit that the soul as a spiritual intelligence comprehends the reality of the existence of Hashem. It understands not only the fact of His existence, but something of His nature, i.e. it fathoms why He should be honored, and reacts to Him with reverence.
Why do our conscious selves not have this clarity? Because we are not disembodied souls. Our neshamos are conjoined to our physical selves. The material substance of those bodies separates us from and intervenes between our souls and our Heavenly Father, Who is entirely spiritual. We compensate for this disability through the Torah, which acts to purify and refine our physical substance so that it interferes with less of the connection between our souls and Hashem. [It was this concept that Chazal had in mind when they said “From the time that the beis hamikdosh was destroyed, an iron barrier separates Yisrael from their Father in heaven.”]
At first blush, we would assume that the Torah can only act as a corrective, restoring our clarity to what it was before our souls became mired in physical bodies. Torah, we would think, refines the physical so that it interferes less with the spiritual presence of Hashem that the soul comprehends. We would not think that Torah could do more than that – that it could allow us to comprehend more than the pure spiritual essence of a soul could comprehend.
We would be wrong to make this assumption, however. The Torah is in fact a tool to whittle away at the layers of obstruction between our souls and Hashem. But it is more than that. Torah is more akin to an optical instrument that allows us to make out a thousand times more detail than the naked eye can. Torah is more than a corrective. It can change the physical to turn it into a looking glass through which the eyes of the soul “see” more than in their natural state.
We can return to the verse we cited above. “From my flesh I behold my G-d.” The verb is not er’eh, but echezeh. The former conveys “seeing” in the conventional sense; the latter is related to chizayon, a vision, of the kind that takes one beyond typical abilities. Through Torah, a person hones his very soul into a more precise instrument with which to sense G-d.
We find that the primordial serpent and Yonah’s sea-animal “heard” Hashem. Animals can respond to Hashem’s will. There is nothing particularly elevated or prophetic about this. It is part of their nature. You will never find an animal described, however, as “seeing” G-d. That is reserved for souls of stature.
Before the sin, Adam’s physical being was of the refined, elevated kind. It was for this reason that clothing was irrelevant to him. No part of the body was associated with lust or desire. This changed with his eating from the Tree of Knowledge. His physicality became coarse and unrefined. It intervened between himself and his Creator. It introduced behaviors and inclinations that separated him from G-d: lust, anger, revenge, imaginative journeys into evil. [These newly-introduced thoughts may be part of what Chazal meant when they wrote that for 130 years after the births of Kayin and Hevel, the first couple brought progeny of spirits and demons into the world.]
In this altered state, Adam and Chavah lost the clarity they had earlier possessed. Now, they merely “heard the sound of Hashem” – but no longer “saw” Him. From that point on and for quite some time, no one is described as seeing Hashem. He speaks to various people, but no one “sees” – until Avraham arrives in the land of Israel. Coming into the Holy Land elevated and refined his physicality, and propelled him to the level of Adam before the sin.
The beginning of the next sidrah in the Torah begins with “Hashem appeared to Avraham and said,” meaning that before the “conversation” took place, Avraham comprehended Hashem in a way that he had not previously. This was so significant to Avraham, that he felt compelled to mark the occasion. He therefore built an altar to “Hashem Who appeared to him.”
From this point on, others would also “see” Hashem. In fact, each of the avos merited this enhanced relationship with Him. The clarity that each one received became part of the legacy they imparted to us to this very day.
 Based on Meshech Chochmah, Lech Lecha 12:7
 Iyov 19:26
 Berachos 32B
 Eruvin 18B
 Bereishis 3:8 The Torah speaks of hearing, rather than seeing, in 3:9 and 3:10 as well