The Magen David Series - Aharon
G-d told Moshe what to say to Pharaoh while in Egypt concerning the approaching ten plagues, and Aharon, Moshe’ older brother, then announced the prophecies to the king of Egypt. In the desert Aharon was anointed Kohen Gadol (high priest) over the nation of Israel, officiating services at the holy Mishkan (Tabernacle). Aharon’s descendants became the Kohanim (priest class) who continued to manage prayers and sacrifices in the Mishkan and both Beit HaMikdashim (Holy Temples) in Jerusalem, and give the Birkat Kohanim (Blessing of the Priests) in every synagogue to this day.
Text from the calendar "Hebrew Illuminations"