The Torah appears to give a similar rationale for both sets of stones. With regard to the stones on the efod, 28:12 records "You are to place the two stones on the should-pieces of the efod, as stones of remembrance for the Children of Israel. Aharon is to bear their names before the presence of G-d on his two shoulders for remembrance." Similarly, 39:7 records, "They placed them (the stones) on the should-pieces of the efod, as stones of remembrance for the Children of Israel." This idea of remembrance also appears by the stones of the hoshen. 28:29 records, "So Aharon is to bear the names of the children of Israel on the hoshen ha-mishpat over his heart, whenever he comes into the Holy-Shrine for remembrance, before the presence of G-d, regularly." (All translations from Fox, 1995.)
We see that both sets of stones relate to remembering, but who was to remember? What was to be remembered? Furthermore, why was there a need for two sets of stones to cause something to be remembered?
One approach (Rashi on 28:12, Seforno on 28:12,29) is that the stones were for G-d to remember the righteousness of the Jewish people. Rashbam (on 28:36) explains that due to this remembering, G-d would forgive the people for their sins. This approach is difficult theologically since it hard to understand why G-d would need to see the stones to be reminded of the righteousness of the Jewish people.
A second approach is that the stones were for the high priest to remember the Jewish people. Benno Jacob writes (1992, p. 918) with regard to the stones of the hoshen that "the high priest did not pray for his people through words in this service, but the names placed upon his heart told G-d what lay in his heart and for whom he sought healing." Similarly with regard to the stones of the efod, he writes (p. 921), that "the two shoulder stones led him to bear the worries of the individual Israelites upon his shoulder."
Cassuto suggests a similar rationale. He writes (1967, p. 374) that the stones of the efod "were a memorial and symbol that the priest ministers in the name of the tribes of Israel." Similarly, with regard to the stones of the hoshen, Cassuto writes (p. 378), "the priest will come before the Lord as the representative of Israel with the names of those whom he represents engraven for remembrance on the pouch (hoshen) that he wears on his heart."
Hertz (1960, pp. 340, 342) follows this idea as he writes by the efod that the "names denoted in concrete form that the high priest was the messenger and representative of the entire community,” and by the hoshen he quotes Benno Jacob’s explanation for the stones. However, by the stones of the efod, he adds another approach that the stones were "to remind the children of Israel of their unity of descent, and unity of service to G-d."
This idea that the high priest was/ is the messenger of the people might seem to be obvious, but as the high priest had relatively limited contact with the people since he was always in the mishkan, Vayikra 21:12, it was possible that he would forget that he was the messenger of the people. The stones on his clothing with the names of the tribes could then have served as a reminder to him that he was a messenger of the people. Furthermore, the idea that the stones on the hoshen were for the high priest to remember that he was a messenger of the people makes sense since the high priest could see the stones on the hoshen which was on chest/ stomach. However, the stones on the efod were on the high priest's shoulders (28:12) and it would have been very hard for him to see them.
Another difference between the two sets of stones is that with regard to the stones on the hoshen, 28:29 records that the stones were to be on his heart, lev. The word lev in the Torah refers to thinking (see our discussion on Devarim 6:5-9, 11:18-20, "Expressions of love") and then the idea of 28:29 is not just the placement of the stones, but also that they are to cause the high priest to think or to remember. However, this reference to the heart/ thinking by the high priest is not recorded in reference to the stones on the efod.
A third difference is that by the efod, the Torah refers to the stones as a zichron le-bnei yisrael, 28:12, 39:7, but this phrase does not appear by the hoshen. The phrase zichron le-bnei yisrael also appears in Bemidbar 17:5, which records that the fire-pans used in the test by the 250 rebels against Moshe and Aharon were to be a covering on the altar to be a lesson for the Jewish people. We see from this case that the phrase, zichron le-bnei yisrael, can refer to the Jewish people, and this implies that the stones on the efod were the Jewish people to remember.
These three differences between the sets of stones imply that the remembering by each set of stones differs. A possible distinction is that the remembering by the stones of the efod was for the Jewish people to remember, while the remembering by the stones of the hoshen was for the high priest, Aharon, to remember.
The question then is what were the Jewish people to remember when they saw the stones on the efod/ shoulders of the high priest? A possible answer is that the stones on the high priest's shoulders would look like a type of pillar of stones, and this could recall the pillars, matzevah, that Moshe put up by the ceremony by the establishment of the covenant, 24:4, as the pillars were a pile of stones. Furthermore, it might be that the matzevah in 24:4 was to re-call the people standing at the foot of Mount Sinai, 19:17, by the Decalogue. Thus, the stones on efod/ shoulders of the high priest might have been to re-call the ceremony by the establishment of the covenant or the Decalogue.
Accordingly, I believe that the stones on the hoshen were for the high priest to remember that he was a messenger of the people, and the stones on the efod were for the Jewish people to either re-call the covenant or the Decalogue.
One approach (Rashi on 28:12, Seforno on 28:12,29) is that the stones were for G-d to remember the righteousness of the Jewish people. Rashbam (on 28:36) explains that due to this remembering, G-d would forgive the people for their sins. This approach is difficult theologically since it hard to understand why G-d would need to see the stones to be reminded of the righteousness of the Jewish people.
A second approach is that the stones were for the high priest to remember the Jewish people. Benno Jacob writes (1992, p. 918) with regard to the stones of the hoshen that "the high priest did not pray for his people through words in this service, but the names placed upon his heart told G-d what lay in his heart and for whom he sought healing." Similarly with regard to the stones of the efod, he writes (p. 921), that "the two shoulder stones led him to bear the worries of the individual Israelites upon his shoulder."
Cassuto suggests a similar rationale. He writes (1967, p. 374) that the stones of the efod "were a memorial and symbol that the priest ministers in the name of the tribes of Israel." Similarly, with regard to the stones of the hoshen, Cassuto writes (p. 378), "the priest will come before the Lord as the representative of Israel with the names of those whom he represents engraven for remembrance on the pouch (hoshen) that he wears on his heart."
Hertz (1960, pp. 340, 342) follows this idea as he writes by the efod that the "names denoted in concrete form that the high priest was the messenger and representative of the entire community,” and by the hoshen he quotes Benno Jacob’s explanation for the stones. However, by the stones of the efod, he adds another approach that the stones were "to remind the children of Israel of their unity of descent, and unity of service to G-d."
This idea that the high priest was/ is the messenger of the people might seem to be obvious, but as the high priest had relatively limited contact with the people since he was always in the mishkan, Vayikra 21:12, it was possible that he would forget that he was the messenger of the people. The stones on his clothing with the names of the tribes could then have served as a reminder to him that he was a messenger of the people. Furthermore, the idea that the stones on the hoshen were for the high priest to remember that he was a messenger of the people makes sense since the high priest could see the stones on the hoshen which was on chest/ stomach. However, the stones on the efod were on the high priest's shoulders (28:12) and it would have been very hard for him to see them.
Another difference between the two sets of stones is that with regard to the stones on the hoshen, 28:29 records that the stones were to be on his heart, lev. The word lev in the Torah refers to thinking (see our discussion on Devarim 6:5-9, 11:18-20, "Expressions of love") and then the idea of 28:29 is not just the placement of the stones, but also that they are to cause the high priest to think or to remember. However, this reference to the heart/ thinking by the high priest is not recorded in reference to the stones on the efod.
A third difference is that by the efod, the Torah refers to the stones as a zichron le-bnei yisrael, 28:12, 39:7, but this phrase does not appear by the hoshen. The phrase zichron le-bnei yisrael also appears in Bemidbar 17:5, which records that the fire-pans used in the test by the 250 rebels against Moshe and Aharon were to be a covering on the altar to be a lesson for the Jewish people. We see from this case that the phrase, zichron le-bnei yisrael, can refer to the Jewish people, and this implies that the stones on the efod were the Jewish people to remember.
These three differences between the sets of stones imply that the remembering by each set of stones differs. A possible distinction is that the remembering by the stones of the efod was for the Jewish people to remember, while the remembering by the stones of the hoshen was for the high priest, Aharon, to remember.
The question then is what were the Jewish people to remember when they saw the stones on the efod/ shoulders of the high priest? A possible answer is that the stones on the high priest's shoulders would look like a type of pillar of stones, and this could recall the pillars, matzevah, that Moshe put up by the ceremony by the establishment of the covenant, 24:4, as the pillars were a pile of stones. Furthermore, it might be that the matzevah in 24:4 was to re-call the people standing at the foot of Mount Sinai, 19:17, by the Decalogue. Thus, the stones on efod/ shoulders of the high priest might have been to re-call the ceremony by the establishment of the covenant or the Decalogue.
Accordingly, I believe that the stones on the hoshen were for the high priest to remember that he was a messenger of the people, and the stones on the efod were for the Jewish people to either re-call the covenant or the Decalogue.