In the Beis Hamikdash they blew Shofar even when Rosh Hashana was Shabbos. The Maamar explains the idea of pnimiyus (vs. chitzoniyus), order and hiskalelus (as opposed to ribuy in Golus; Tzadik vs. Baal teshuva) that existed in the time of the (1st) Beis Hamikdash. The aguda achdus in the time of the Beis Hamikdash allowed for the deeper internalizing of the Atzmus brought down through Shabbos and Shofar, there was therefore a point in blowing Shofar on Shabbos as well. We are not in that position. However, even nowadays the Pesukim are read 1) to reveal the Atzmus brought on by Shabbos (that achieves what the Shofar would during the week), 2) that the Atzmus of Shofar is (like Yom Kippur) higher than Shabbos and must therefore be read even when Rosh Hashana is Shabbos. Page 545-7, NEW SV p. 718-20. Shecheyanu Vikiyimanu Vihigeanu Lizman Haze!!
