Before the giving of the Torah, Israel was on the level of "angelic beings", "sons of the Most High", and thus the light of Shabbat was given to them directly, not in the limited form of letters but as the unbounded light of Ein Sof. "You must see that G‑d has given you Shabbat" - not as a revelation that can be contained in words, but in a way that can be seen only with the heart. Every Shabbat becomes like the first…
After that, on every succeeding Shabbat, Israel could soar to unprecedented heights, until the previous Shabbat would seem like a weekday in comparison. This is because on every Shabbat there shines a light that can make one feel that he has never observed a Shabbat before. Every Shabbat becomes like the first. Hence the Talmud teaches that if Israel had only kept the first Shabbat, they would immediately have been redeemed, meaning to say that every Shabbat is "a first Shabbat" from the viewpoint of the new light created for that individual Shabbat.
This is how it was supposed to be, before the sin of the Golden Calf, when the Israelites were still on an exalted spiritual level. Before the sin they could, on their own, draw the higher consciousness of Shabbat from its very Source. Hence, the seven Shabbat jewels would only have clouded their Divine awareness and prevented their contact with the Infinite Light. The amount of light revealed to them would be in direct proportion to the intensity of their spiritual longing…
After the sin, however, when they could no longer relate to Shabbat from the viewpoint of "sight and perception", the seven jewels of Shabbat had to be spelled out to them. Their physical letters would become conduits through which the Israelites would absorb the light and benefit from it. Nevertheless, even after the sin of the Golden Calf, those righteous people who had achieved a degree of holiness were still able to experience Shabbat in all its original radiance.
"I have a precious gift among My hidden treasures, and Shabbat is its name. Go and inform the Israelites", said G‑d to Moses after the Golden Calf. The Almighty was saying that although the sin had dimmed the people's ethereal lights and that from then on they would have to exert themselves considerably to regain the light, still the gift of Shabbat was that its light was not obstructed by their physicality like all the other lights. On Shabbat, they would be able to absorb the light of the Torah without the effort required during the week. On every Shabbat, the amount of light revealed to them would be in direct proportion to the intensity of their spiritual longing.
We must learn how to focus our minds on G‑d with increasing sharpness, until the myopia we have inherited from the perpetrators of the Golden Calf completely falls away.
[From "Living the Kabbalah: A Guide to the Sabbath and Festivals in the Teachings of Rabbi Rafael Moshe Luria".]