The number 15 is significant in Judaism in various ways.
It is the date when both Pesach (15 Nisan) and Succot (15 Tishri) begin, and the Talmud finds common halachic features between the two festivals based on this confluence of dates.
Fifteen is also the date of three ‘minor festivals’. The first of these is 15 Shevat, the New Year for Trees, when it has become customary to eat 15 different kinds of fruit.
Interestingly, the second is 15 Av, which the Mishnah tells us used to be one of the two happiest days in the Jewish calendar – alongside Yom Kippur!
The Talmud tells us 15 Av was the day when the various Israelite tribes were first permitted to intermarry – in the era of the Judges – thereby abolishing the Torah’s temporary ban on this.
It was also when border restrictions established by Jeroboam, ruler of the 10 northern tribes of Israel, were removed.
The 15 Av also marks the date the Roman government finally gave permission for Jews killed at Bethar, part of the Bar Kochba revolt, to be decently buried.
Our third ‘minor’ festival is Shushan Purim celebrated annually as Purim – on 15 Adar – by the residents of Jerusalem and all cities surrounded by a wall from the time of Joshua.
It is surely no coincidence that all these joyful occasions occur on 15th of the month, when the moon is at its fullest and attains its maximum size and brightness.
Our sages compare the Jewish people to the moon: just when they are at their nadir and about to vanish from history, they invariably re-emerge in their full splendour.
Finally, we have the 15 Songs of Ascent composed by David and Solomon, and recited by the Levites making their ceremonial ascent, via 15 steps, in the Temple, every Succot.
To this day, they are recited every Shabbat afternoon during the winter months, thereby acknowledging their immense historical and spiritual significance.
Dina Golker is the assistant rebbetzin of St John’s Wood Synagogue