The Torah records the arrival at Sinai with a precise phrase (Exodus 19:1): "On this day they came to the desert of Sinai." The Mekhilta de-Rabbi Ishmael identifies the exact date concealed in these words: it was Rosh Chodesh, the first day of the third month, the new moon of Sivan.
This seemingly simple calendrical note carries enormous weight. The Israelites had left Egypt on the fifteenth of Nisan. They crossed the Red Sea, received water at Marah, arrived at Elim with its twelve springs and seventy palm trees, grumbled for food in the Wilderness of Sin, fought Amalek at Rephidim—and then, on the first day of Sivan, they reached the mountain where God would give them the Torah. The entire sequence from Exodus to Revelation took roughly seven weeks, a span that would later be commemorated as the counting of the Omer leading to the festival of Shavuot (the Festival of Weeks).
The Mekhilta's identification of Rosh Chodesh is not arbitrary. The new moon symbolizes renewal and fresh beginnings in Jewish tradition. Israel arrived at Sinai not in the middle of an ordinary month but at its very start—a clean slate, a new cycle, a moment of cosmic reset. Everything that had come before—the slavery, the plagues, the sea, the hunger, the battles—was prologue. The real story was about to begin.
By pinpointing the date, the rabbis also anchored the revelation at Sinai in historical time. This was not a myth floating outside of chronology. Moses and Israel arrived at a specific place on a specific day, and the preparations for receiving the Torah began from that precise moment. The Mekhilta treats the Torah's dates the way historians treat primary sources: as evidence that these events happened in real time, on a real calendar, under a real sky.