Musar do Wyjścia 25:3

We have said that the ladder also alludes to the Holy Temple; we find the concept of the Holy Temple similarly divided into three levels corresponding to the three divisions of the letters in the alphabet. The first set of donations for the Tabernacle mentioned in the Torah (Exodus 25, 3) comprises זהב, כסף, ונחשת, gold silver and copper. Gold always represents something "above," copper something "below," whereas silver corresponds to the elements bridging the gap between what is above and what is below. The seven arms of the candelabra, which provide spiritual illumination, correspond to the seven major planets which illumine the physical world. The twelve precious stones that the High Priest wore in his breastplate, the אבני זכרון, correspond to the significance of the group of twelve letters, and the 12 מזלות. We see how in the word וישכב, which we divided into the two words יש-כב, all these concepts are represented, and why the Mishnah in Uktzin spoke about 310 = יש reserved for the Jewish people.