(Exodus 12:2) records God's instruction to Moses: "This month shall be to you the beginning of months." It is the very first commandment given to Israel as a nation, even before the exodus from Egypt was complete. Rabbi Yishmael explains what happened next in a detail that transforms our understanding of how the Jewish calendar works.
Moses did not simply relay God's words to the people. He pointed at the sky. Specifically, he pointed at the new moon, the thin sliver of light that marks the beginning of each Hebrew month. He showed it to Israel and said: this is what it looks like. When you see the moon in this phase, that is when you declare a new month.
The phrase "thus shall it look" is the key. Moses was giving the people a visual standard, not just a verbal instruction. Future generations would need to know exactly what the new moon looked like in order to establish the calendar correctly. Every holiday, every Sabbath-adjacent calculation, every agricultural cycle depended on getting this right.
Rabbi Yishmael's reading establishes that the new month was determined by direct observation. Real people looked at the real sky and compared what they saw to the standard Moses had shown. This was not an abstract mathematical calculation. It was empirical. Witnesses would appear before the court, describe the moon they had seen, and the court would declare the new month based on their testimony.
The Mekhilta preserves the moment when Moses first established this practice, pointing upward and teaching all future generations how to read the heavens.