The sidra gives an example. Hachodesh ha-zeh lachem rosh chodashim, it says: “This month shall be to you the first of the months” (Ex. 12:2).
According to Rabbi Akiva, the crucial word here is ha-zeh – “this”.
It is one of three places in the Torah where Moses asked for a visible illustration, something he could see.
The first instance was the calendar. “When the moon is like this, it is a new moon – and this is to be the first of them”.
The second was the menorah: “This is the menorah you shall make, its shape and ornamentation”.
The third was the dietary laws: with the word “this”, Moses was shown the appearance of the creatures that were not to be used as food.
The three examples are more than random coincidence. Each represents a basic dimension of Judaism.
First comes the calendar. Samson Raphael Hirsch said that the creed of a Jew consists of his calendar: if you know which occasions Jews esteem, you know what Judaism believes in.
Then comes the menorah, which is symbolic of the light of learning and understanding: if you have Jewish knowledge, you have Judaism.
Third is the dietary laws and the other practical observances: if you see how Jews live their life, you have a yardstick of their Jewishness.